A kotatsu (炬燵, 火燵 or こたつ) is a traditional type of Japanese heater-table.

Structurally, a kotatsu is a low, open wooden frame covered by a blanket, upon which a table top sits. Underneath is a heat source, often built into the table itself.

There are two kinds of kotatsu in use today. One consists of a table with an electric heater attached to the underside of the frame. The other type is a pit about 40 centimeters deep that is cut into the floor. An electric heater is placed inside and a table-top and frame arranged over it.

Generally, a futon is draped over the frame under the table-top.