To provide a standing assist chair safely used by preventing a user from frontward slipping off in a process of changing a posture when the user with disabled lower legs secures a standing state from a sitting state.

This apparatus is characterized in that a seat frame is pivotally provided with a cusp type saddle part 1 fitted to a seat chair part 12 and supporting the crotch and the buttocks, and a lifting curved arm 15; a lifting mechanism 4 is driven to tiltingly lift/lower the seat chair part 12; the cusp type saddle part 1 is suddenly raised by driving a lifting mechanism 4" to support the crotch part and the buttocks and eliminate the slipping off of the upper limbs.