A cylinder device comprising: a housing; a piston (5, 59, 150) inserted in the housing, the piston (5, 59, 150) being configured to move in an axial direction to a lock side and to a release side; a first detection valve (12, 64, 121) provided to the housing, the first detection valve (12, 64, 121) being configured to detect an operational state of the piston (5, 59, 150); and a second detection valve (13, 65, 122) provided to the housing, the second detection valve (13, 65, 122) being configured to detect the operational state of the piston (5, 59, 150), an air supply passage (16, 67 and 68, 124) which is provided to the housing and through which air functioning as fluid for detection is supplied to the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) in this order; an air discharge passage (18, 69, 127) which is provided to the housing and through which air having been supplied to the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) from the air supply passage (16, 67 and 68, 124) is discharged; at least one air passage (14 and 15, 66, 125 and 126) provided to the housing, the air passage (14 and 15, 66, 125 and 126) communicatively connecting the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) to each other in series in order to supply air from the first detection valve (12, 64, 121) to the second detection valve (13, 65, 122), wherein the second detection valve (13, 65, 122) among the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) is configured as a throttle detection valve (13, 65, 122) including a throttle passage (56a, 106, 107a, 149). a housing; a piston (5, 59, 150) inserted in the housing, the piston (5, 59, 150) being configured to move in an axial direction to a lock side and to a release side; a first detection valve (12, 64, 121) provided to the housing, the first detection valve (12, 64, 121) being configured to detect an operational state of the piston (5, 59, 150); and a second detection valve (13, 65, 122) provided to the housing, the second detection valve (13, 65, 122) being configured to detect the operational state of the piston (5, 59, 150), an air supply passage (16, 67 and 68, 124) which is provided to the housing and through which air functioning as fluid for detection is supplied to the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) in this order; an air discharge passage (18, 69, 127) which is provided to the housing and through which air having been supplied to the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) from the air supply passage (16, 67 and 68, 124) is discharged; at least one air passage (14 and 15, 66, 125 and 126) provided to the housing, the air passage (14 and 15, 66, 125 and 126) communicatively connecting the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) to each other in series in order to supply air from the first detection valve (12, 64, 121) to the second detection valve (13, 65, 122), wherein the second detection valve (13, 65, 122) among the first detection valve (12, 64, 121) and the second detection valve (13, 65, 122) is configured as a throttle detection valve (13, 65, 122) including a throttle passage (56a, 106, 107a, 149).