To provide a backrest for a handrail by means of which, when a chair is installed along an existing handrail, an available floor area is maximized.

The backrest 11 for a handrail is freely removably installed relative to a handrail 12 supported on a bracket 17 projectingly provided on a wall face 16 of a building. The backrest 11 for a handrail includes: a locking portion 13 hooked on a handrail 12; a backrest portion 14 mounted with the locking part 13, and formed in a long plate shape along the longitudinal direction of the handrail 12; and a gap adjusting portion 15 provided along the longitudinal direction in the lower part of the rear face of the backrest portion 14.