An apparatus for inspecting automatic lock sliders comprises a table for horizontally holding and intermittently moving sliders, an elevating board disposed above the table and adapted to be reciprocated vertically at a predetermined stroke while the table is at a stop, an auxiliary support block attached slidably to the elevating board so as to be vertically reciprocated above the slider held on the table, and a retainer rod and a pressure rod both attached to the auxiliary support block as allowed to reciprocate vertically and elastically urged downwardly. By interposing a decelerating mechanism between the elevating board and the auxiliary support block, the speed of reciprocation of the retainer rod and the pressure rod is decreased relative to that of the elevating board just before and after a sensing projection of a sensor lever pivotally supported on the retainer rod collides against a pull tab of the slider and the otherwise possible accidental jump of the sensor lever due to the collision is prevented. The inspection of the slider to discriminate between acceptability and rejectability thereof is attained by causing the pressure rod to exert pressure on the pull tab and detecting the motion of the sensor lever owing to the pivotal movement of the pull tab caused by the pressure.