Bonshō (梵鐘, Buddhist bells), also known as tsurigane (釣り鐘, hanging bells) or ōgane (大鐘, great bells) are large bells found in Buddhist temples throughout Japan, used to summon the monks to prayer and to demarcate periods of time. Rather than containing a clapper, bonshō are struck from the outside, using either a handheld mallet or a beam suspended on ropes.

The bells are usually made from bronze, using a form of expendable mould casting. They are typically augmented and ornamented with a variety of bosses, raised bands and inscriptions. The earliest of these bells in Japan date to around 600 CE, although the general design is of much earlier Chinese origin and shares some of the features seen in ancient Chinese bells. The bells' penetrating and pervasive tone carries over considerable distances, which led to their use as signals, timekeepers and alarms. In addition, the sound of the bell is thought to have supernatural properties; it is believed, for example, that it can be heard in the underworld.

The spiritual significance of bonshō means that they play an important role in Buddhist ceremonies, particularly the New Year and Bon festivals. Throughout Japanese history these bells have become associated with stories and legends, both fictional, such as the Benkei Bell of Mii-dera, and historical, such as the bell of Hōkō-ji. In modern times, bonshō have become symbols of world peace.

The bonshō is derived from the bianzhong (henshō (編鐘) in Japanese), an ancient Chinese court instrument comprising a series of tuned bells. One larger additional bell, which eventually developed into the bonshō, was used as a tuning device and a summons to listeners to attend a bianzhong recital. According to legend, the earliest bonshō may have come from China to Japan via the Korean Peninsula. The Nihon Shoki records that Ōtomo no Satehiko brought three bronze bells back to Japan in 562 as spoils of war from Goguryeo.

Bonshō are cast in a single piece using two moulds, a core and a shell, in a process that is largely unchanged since the Nara period (710–794). The core is constructed from a dome of stacked bricks made from hardened sand, whilst the shell is made using a strickle board. This is a large, flat, wooden board shaped like a cross-section of the bell, which is rotated around a vertical axis to shape the clay used for the mould. Inscriptions and decorations are then carved or impressed into the clay. The shell fits over the core to create a narrow gap, into which the molten bronze is poured at a temperature of over 1,050 °C (1,920 °F). The ratio of the alloy is usually around 17:3 copper to tin; the exact admixture (as well as the speed of the cooling process) can alter the tone of the end product. After the metal has cooled and solidified, the mould is removed by breaking it, therefore a new one has to be created for each bell. The process has a high failure rate; only around 50 per cent of castings are successful on the first attempt, without cracks or imperfections.

The casting is traditionally accompanied by the chanting of Buddhist sutras, which may go on for several hours. Buddhist prayer papers, sprigs of sacred mulberry and other ceremonial offerings are added to the molten bronze during the founding process.

There are several parts to a temple bell:

Some bells retain linear impressions arising from joints in the mould used; they are not removed during fettling but are regarded as an aspect of the bell's overall beauty. The bell's appearance and sound are intended to be in keeping with Japan's wabi-sabi aesthetic.