Shōzō Shimamoto (嶋本 昭三, Shimamoto Shōzō; January 22, 1928 – January 25, 2013) was a Japanese artist. Having studied with Jirō Yoshihara, the future Gutai leader, from 1947, Shimamoto was a key founding member of Gutai along with Yoshihara and fifteen others in August, 1954. He was close to the leader Yoshihara and actively engaged in the early activities and group administrations. He worked with a wide variety of techniques, such as poking holes in layered newspaper, throwing bottles of paint at canvases, experimenting with film and stage performances, and composing sound art. He was particularly noted for his innovative performance art. Indeed, when Yoshihara turned to focus more on painting, upon his meeting with the French art critic Michel Tapié, Shimamoto continued to urge the leader to pursue this direction, wanting to work with Allan Kaprow, for example.

After Gutai, he became known for his mail art activities with the group AU and the continuation of his painting performances which he staged around the world. He died of acute heart failure in Nishinomiya City, Hyōgo prefecture.

Shimamoto was a student of Yoshihara’s beginning when he was nineteen, in 1947.

In 1950, he graduated from the School of Humanities, Kwansei Gakuin University in 1950.

Shimamoto has cited the calligraphy work of Nantembō as an early influence, noting that “The thing that surprised me most when I went to see this master was that he used a very large paintbrush and with this he created much larger works than he contemporaries.” Of his early works from 1950 he has described “a single arrow sign on a piece of paper, a picture of only one circle drawn on the canvas, and a hole made on the center of the canvas, etc.” The latter of these refers to his “Hole” series, in which he perforated the picture plane of the painting. These works were developed out of the economic conditions following the Second World War and his inability to afford canvas. By glueing together layers of newspaper, he created a new kind of support which he called “paper-vas.” The paper-vas was adhered with a glue made from flour and water, onto which a final layer of brown cartridge paper was glued and then painted white. He found that when painting the support would tear where the glue had not dried completely. The tearing of the support inspired him to make a series of works with perforated paper-vas, resulting in artworks like his 1950 Work (Holes). In this work, the white, monochromatic surface appears on the verge of crumbling from a series of aggressive pencil gestures. A similar work, Holes (1954), is in the collection of the Tate Modern.

Prior to these works, Yoshihara had been little impressed by Shimamoto's efforts, discouraging him from pursuing painting as a career after some time. Motivated by the challenge, Shimamoto promised him a painting that hadn't been painted before. This caused Shimamoto to create the first paper-vas work, for which Yoshihara enthusiastically praised him. Shimamoto recounted that when he had shown his first Hole work to Yoshihara, they “both felt that something great had been accomplished.” He then locked himself in his room and produced more using the same method to which Yoshihara, according to Shimamoto, “gave them a glance and just told me that he had seen this stuff before.” Yoshihara discouraged him from continuing the series when they first encountered the “buchi” works of Lucio Fontana which also pierce the surface of the painting. Although the works were made contemporaneously and without knowledge of one another (according to Shimamoto), Yoshihara felt that Shimamoto's works would inevitably be regarded as derivative due to biases of the art world at the time. As Alexandra Munroe suggests, these works “defiantly opposed established notions of permanence in abstract modernist painting and introduced hin (poverty)—the appreciation of minimal and naturally weathered objects as cultivated in the arts of tea— into the context of contemporary Japanese art.” As such, the Hole series “represents the beginning of a Gutai Style” for Munroe.

In 1954, Shimamoto participated in the “Second Genbi Exhibition,” showcasing the artist of the Gendai Bijutsu Kondankai (Contemporary Art Discussion Group) started by Hiroshi Muramatsu and strongly influenced by Yoshihara. The group sought to rethink hierarchy on every level of the art world. The exhibition, held at the Asahi Biru Gallery in Kobe, brought together many young Kansai-based artists who would soon establish Gutai with Yoshihara. Shimamoto was responsible for proposing the name Gutai, translated from Japanese as “concrete” or “embodied.” Of this name he has explained, “We did not want to show our feeling indirectly or abstractly.” Shimamoto is also responsible for approaching members of the Zero-kai group, Kazuo Shiraga, Saburo Murakami, Atsuko Tanaka, and Akira Kanayama, to join Gutai after some of the initial members left. Shimamoto's house became the first headquarters for the group, and is where the first Gutai journal was published.

Shimamoto also contributed to Gutai through his writing, published in the Gutai journal. This attitude toward painting is also shown in his 1957 text “The Idea of Executing the Paintbrush,” in which he writes, “I believe that the first thing we should do is to set paint free from the paintbrush.” He furthermore advocates the recognition that “a color without matiére cannot exist” and that therefore the artist should paint in a manner that “takes advantage of the texture of the paint and gives it a lively feeling.” In one article, “Mambo and Painting,” Shimamoto argued for the destruction of “the values established by the art elite” through the creative incorporation of audience participation. In opposition to the art “elite,” Shimamoto wrote, “it would never due for those elitist to consider a masterpiece a painting made by dancing the mambo on a canvas.”