A driving chamber (11) where pressurized fluid is supplied and discharged is arranged above a piston (10) inserted into a housing (1) ascendably and descendably. An ascent-detecting detection valve (32) is oriented laterally in an upper portion of the housing (1). An operating portion (10b) is provided on an upper portion of the piston (10), and an operated portion (79) movable in response to movement of the operating portion (10b) is provided on the detection valve (32). A transmission ball (70) is inserted into a transmission chamber (67) communicatively connected to an upper portion of the driving chamber (11). The transmission ball (70) converts ascent movement of the operating portion (10b) to lateral movement of the operated portion (79). Pressurized air for detection is supplied to an inlet (32a) of the detection valve (32) through a supply passage (B2).