To prevent the breakage of a member without impairing the easiness of the attachment of an operation lever, in a lever unit of a chair.

The lever unit 45 is constituted of the operation lever 25 and a mount member 43. The mount member 43 has a base plate 54 fixed to a base 6 and receiving parts 56 which are integrally attached to fore-and-aft both ends of the base plate 54 via hinges 57. Bearing holes 58 are formed at the receiving parts 56, and a shaft 46 of the operation lever 25 is fit into the bearing holes 58. The shaft 46 can be fit into the bearing holes 58 by expanding a clearance between the fore-and-aft receiving parts 56. The receiving parts 56 are fit into recesses 59 and held so as not to fall down by fixing the mount member 43 to a receiving seat. When turning the receiving pats 56, since loads are not applied to the hinges 57, there does not occur such a problem that the mount member 43 is broken.