Machiya (町屋/町家) are traditional wooden townhouses found throughout Japan and typified in the historical capital of Kyoto. Machiya ('townhouses') and nōka ('farm dwellings') constitute the two categories of Japanese vernacular architecture known as minka ('folk dwellings').

Machiya originated as early as the Heian period and continued to develop through to the Edo period and even into the Meiji period. Machiya housed urban merchants and craftsmen, a class collectively referred to as chōnin ('townspeople').

The word machiya is written using two kanji: machi (町, 'town') and ya (家, 'house') or ya (屋, 'shop'), depending on the kanji used to express it.

Machiya in Kyoto, sometimes called kyōmachiya (京町家/京町屋), formed the defining characteristic of downtown Kyoto architecture for centuries, representing the standard defining form of the machiya throughout the country.

The typical Kyoto machiya is a long wooden home with narrow street frontage, stretching deep into the city block and often containing one or more small courtyard gardens, known as tsuboniwa. Machiya incorporate earthen walls and baked tile roofs, and are typically one, one and a half or two stories high, occasionally stretching to three stories. The front of the building traditionally served as the retail or shop space, known as mise no ma (店の間, lit. 'shop space'), typically having sliding or folding shutters that could open to display goods and wares. The plot's width was traditionally an index of wealth, and typical machiya plots would be just 5.4 to 6 metres (18 to 20 ft) wide but 20 metres (66 ft) deep, leading to the nickname unagi no nedoko (鰻の寝床), or 'eel beds'.

Behind the shop space, the remainder of the main building would be divided into the kyoshitsu-bu (居室部, lit. 'living room'), composed of divided rooms with raised timber floors and tatami mats coverings. Machiya would also feature a doma (土間) or tōriniwa (通り庭), an unfloored earthen service space that contained the kitchen, also serving as the passage to the rear of the plot, where storehouses known as kura (倉/蔵) would be found.

A hibukuro (火袋) above the kitchen would serve as a chimney, carrying smoke and heat away, and also serve as a skylight, bringing light into the kitchen.

The largest residential room in a machiya, located in the rear of the main building and looking out over the garden which separated the main house from the storehouse, was known as the zashiki (座敷), and doubled as a reception room for special guests or clients. The sliding doors which made up the walls in a machiya, as in most traditional Japanese buildings, provided a great degree of versatility; doors could be opened and closed or removed entirely to alter the number, size, and shape of rooms to suit the needs of the moment. Typically, however, the remainder of the building might be arranged to create smaller rooms, including an entrance hall or foyer (genkan (玄関)), butsuma (仏間), naka no ma (中の間) and oku no ma (奥の間), both of which mean simply 'central room'.