Hanafuda (Japanese: 花札, lit. 'flower cards') are a type of Japanese playing cards. They are typically smaller than Western playing cards, only 5.4 by 3.2 centimetres (2.1 by 1.3 in), but thicker and stiffer. On the face of each card is a depiction of plants, tanzaku (短冊; 'paper strips'), animals, birds, or man-made objects. One single card depicts a human. The back side is usually plain, without a pattern or design of any kind, and traditionally colored either red or black. Hanafuda are used to play a variety of games including Koi-Koi and Hachi-Hachi.

In Korea, hanafuda are known as hwatu (Korean: 화투, Hanja: 花鬪, 'flower battle') and made of plastic with a textured back side. The most popular game is Go-stop (Korean: 고스톱), commonly played during special holidays such as Lunar New Year and Chuseok (Korean: 추석).

In Hawaii, hanafuda is used to play Sakura. Hanafuda is also played in Micronesia, where it is known as hanahuda and is used to play a four-person game, which is often played in partnerships.

Playing cards were introduced to Japan by the Portuguese in the mid-16th century. The Portuguese deck consisted of 48 cards, with four suits divided into 12 ranks. The first Japanese-made decks made during the Tenshō period (1573–1592) mimicked Portuguese decks and are referred to as Tenshō Karuta. The main game was a trick-taking game intermediate in evolution between Triunfo and Ombre. After Japan closed off all contact with the Western world in 1633, foreign playing cards were banned.

In 1648, Tenshō Karuta were banned by the Tokugawa shogunate. During prohibition, gambling with cards remained highly popular which led to disguised card designs. Each time gambling with a card deck of a particular design became too popular, the government banned it, which then prompted the creation of a new design. This cat-and-mouse game between the government and rebellious gamblers resulted in the creation of increasingly abstract and minimalist regional patterns (地方札). These designs were initially called Yomi Karuta after the popular Poch-like game of Yomi which was known by the 1680s.

Through the Meiwa, An'ei, and Tenmei eras (roughly 1764–1789), a game called Mekuri took the place of Yomi. It became so popular that Yomi Karuta was renamed Mekuri Karuta. Mechanically, Mekuri is similar to Chinese fishing games. Cards became so commonly used for gambling that they were banned in 1791, during the Kansei era. On the other hand, Uta-garuta such as Hyakunin Isshu were officially permitted as being educationally beneficial. So as a loophole to the ban, early hanafuda were made to have old poems on some of the cards, disguising them as Uta-garuta. Remnants of this can be seen via the tanzaku-ranked cards.

The earliest known reference to hana awase (a previous version of hanafuda) is from 1816 when it was recorded as a banned gambling tool. The earliest decks contained between 12, 20, and even 32 suits, each with one high value card, one tanzaku card, and two low-value cards.

As hana awase modernized into hanafuda, it standardized at 12 months (suits) with four rank-like categories. The majority of hanafuda games are descended from Mekuri although Yomi adaptations for the flower cards survived until the 20th century. Though they can still be used for gambling, its structure and design is less convenient than other decks such as Kabufuda. In the Meiji period, playing cards became tolerated by the authorities.