PURPOSE: To make further compact the size of a lock by providing a click spring which holds a locking part elastically so that it may be substantially at right angles to the sliding direction of an elastic thin sheet-shaped deformation member which forms a pushbutton switch on the side surface.

CONSTITUTION: In the case when a padlock is unlocked, a pushbutton switch 2 of a lock main body 1 is pushed in from the front surface and pushed out to the front surface side from the rear surface side where a pushbutton switch is set respectively to each of specified retractive positions. When the pushbutton switch moves up and down, a click spring member 6 is elastically deformed on upper and lower stages of V-shaped groove engagement areas 10 while the pushbutton switch 2, while moving in the run-away direction, is elastically held by a tapered part 12 of the click spring member 6 substantially from the right angle direction at the upper or lower parts. After every pushbutton switch 2 is set to the specified retractive positions, if a hook-shaped locking part 3 of a locking member 5 is pulled out, each key projection 4 of a U-shaped locking part 4 of the locking member 5 is fitted in a key groove 9 of the head of the pushbutton switch 2 so that the tip of the locking part 3 may be separated from a lock main body 1.