To provide an auxiliary table for a Kotatsu, placed under a chair type study desk to which an existing Kotatus is mounted for warmth by placing an auxiliary table under the chair type study desk.

In this auxiliary table for Kotatus, four vertical supports (2) are connected to an upper frame formed by connecting four lateral supports (1) through upper Y-joints and a lower frame formed by connecting four lateral supports (3) through lower Y-joints through the upper Y-joints and the lower Y-joints. An existing Kotatus is mounted to the auxiliary table for warmth comfortably.