To provide a mounting structure for a lock for a bicycle and the lock for the bicycle allowing easy locking operation without standing on a side of the lock for the bicycle and stooping for pressing a bolt piece.

A bolt piece 3 is movably provided in a lock main body 10 fixed to a front fork 100 of a bicycle by a fixing fitting. The bolt piece 3 is disposed with its axial direction in a vertical oblique direction for a plane P perpendicular to an axle 102 of a wheel 101 of the bicycle. When locking, a tip of the bolt piece 3 is projected between spokes of the wheel 101 to lock the wheel 101 by pressing the bolt piece 3 to an oblique lower side.