To obtain a Kotatsu cover set which can secure a heat retaining property and from which Futon covers can be separated by using a piece of highly heat retaining cloth as a Kotatsu Futon and making a Kotatsu cover composed of a top face section and side face sections which can be attached to and detached from the top face section usable in a twofold state when a user warm himself at a Kotatsu in a sitting state and in a onefold state when the user lies on his side.

A piece of cloth 1 which is as thin as the fleece cloth and has a high heat retaining property is put on a Kotatsu 12 available on the market as the conventional Kotatsu Futon and the top face section 3 of a Kotatsu cover made of a piece of thick washable reversible cloth, such as the quilting cloth, etc., is put on the cloth 1. The Kotatsu cover is usually used in a state where a male Velcros 9 sewn on the top section 3, female Velcros 10 and male Velcro 11 of respective side 5, 6, 7 and 8 are set to foldable states. The connecting sections between the top section 3 and side-face sections 5-8 are concealed with the hanging- down sections 4 of the top face section 3. When the user lies on his side, the Kotatsu cover is set to a onefold state by respectively removing the female Velcros 10 attached to the upper surfaces of the sections 5-8 and the male Velcros 11 attached to the bottoms of and used by covering up to the shoulder like a coverlet.