An apparatus has a configuration in which: a piston (10) is inserted into a housing (1) ascendably and descendably; and pressurized oil is able to be supplied to and discharged from a driving chamber (11) arranged above the piston (10). An output rod (15) inserted into an upper wall (2) of the housing (1) is provided to protrude upward from the piston (10). A descent-detecting first detection valve (31) and an ascent-detecting second detection valve (32) are arranged outside the periphery of the output rod (15) and in the upper wall (2), to be circumferentially spaced apart from each other at a predetermined interval. Each of the first detection valve (31) and the second detection valve (32) has an operated portion (49) (79) which faces the piston (10) from above. The apparatus is configured so that pressurized air for detection is able to be supplied through a first supply passage (B1) and a second supply passage (B2) to respective inlets (31 a) (32a) of the first detection valve (31) and the second detection valve (32), respectively.