To provide a locking mechanism which enables sure locking, even if an urging spring of a locking lever is broken or turning of the locking lever is put into a nonsmooth state.

A back end of the locking lever 20 is molded in a bifurcated shape; first and second operating arms 18 and 19 are formed on both sides of a groove 17 in such a manner that the groove 17, into which a control pin 13 is to be engaged, is sandwiched in between; the control pin 13 is engaged with each of the operating arms when moved forward and backward with a slider 12; and the locking lever 20 is forcedly driven in a locking or unlocking direction by a wedge action which is caused between the operating arm 18 (19) and the control pin 13.