To provide toilet seat apparatus which is allowed to have a caring function and a convenient cleaning function.

In the apparatus, a driving device 10 for vertically moving a toilet seat box 2 has: a step motor; a speed changer 12 connected with the step motor on an input side; a pinion 14 connected to the output side of the speed changer 12; and a rack 16 with which the pinion is meshed. The speed changer 12 is fixed to the front base plate 2a of a toilet seat box 2. The rack 16 is fixed to a frame 18 erected from a rear base plate 8 arranged on a a western style toilet bowl body 1. With the speed changer 12, the output torque of the driving device 10 can be amplified to a torque capable of pushing up the toilet seat box 2 together with a human body mounted thereon against a load of the human body even when the human body is seated on the toilet seat 4.