To provide a chair for a bathroom of which the seat section rotatable in relation to legs is usually locked not to rotate unintentionally and is stably rotated for a long time even when a biased weight is applied.

A rotation mechanism 6 which rotatably supports the seat section 3 in relation to the legs 2 is constituted with a lower attachment member 61 in which two or more engagement holes are formed in a direction of a circumference with prescribed intervals, an upper attachment member 65 which is fixed to the seat section 3 and is rotatably connected to the lower attachment member 61, and two or more supporting rollers 64 which are rotatably supported by pivoting through roller receptacle members 62 at a peripheral part of the lower attachment member 61 respectively in the direction of the circumference with the prescribed intervals. Also, a lock device 7 which usually fixes the seat section 3 not to rotate is constituted with a lock lever 71 which is rotatable supported on the upper attachment member 65 by pivoting, lock pins 72 which can be engaged in engagement holes 61a of the lower attachment member 61, and springs 73 which urges the lock pin 72 in the direction of being engaged with the engagement holes 61a.