To provide a compact chair for waist part exercise allowing efficient and uniform exercise for abdominal muscle, back muscle, and inclination of pelvis in the direction of whole periphery without requiring a large place and a large space and allowing a user to perform other work easily even during use and being simple and easy for continuous medical treatment.

This chair for waist part exercise is provided with an inclination direction change mechanism 2 which brings a seat 1 into an inclined condition in a predetermined direction and lets the seat 1 perform inclination direction change operation in which inclination direction of the seat 1 is continuously changed in the peripheral direction when viewed in a plan without turning a seat face while the user is seated on the seat 1.