A cushion for a baby chair comprises a head pad, a back pad and a buttocks pad arranged on a seat of the baby chair. The head is supported by a neck support portion projecting along a lower edge of the head pad and a pair of temporal support portions projecting along both side edges of the head pad. A trunk is supported from a side by a pair of trunk support portions projecting along both side edges of the back pad and extending from an upper to a lower edge of the back pad. Buttocks are supported by a buttocks support portion projecting along a lower edge of the buttocks pad. A thigh and a knee are supported by a pair of thigh support portions projecting along both side edge of the buttocks pad. The head pad, the back pad, and the buttocks pad are mutually detachable.