A variable displacement type compressor includes a casing having a working chamber and cylinder bores provided therein and opened to face to the working chamber. The cylinder bores are disposed around a driving shaft rotatably carried in the casing. A working piston is slidably received in each of the cylinder bores. A sleeve is axially slidably fitted over the driving shaft within the working chamber and carries a holder mounted for swinging movement about an axis perpendicular to an axis of the driving shaft and connected to the driving shaft. A swingable swash plate is carried on the holder and connected by rods to the working pistons. A control piston is connected to the sleeve and slidably received in the casing to vary the angle of inclination of the holder and the swingable swash plate and vary the stroke of the working pistons. A stroke detecting device detects the operation stroke of the working pistons and includes an interlocking member supported at a middle portion on the casing by a shaft having an axis perpendicular to the axis of the driving shaft and connected at opposite ends to the control piston and a position detector disposed on the casing. The control piston can be relatively rotatably connected to the sleeve to inhibit transmission of rotating movement of the sleeve. The position detector is disposed outside the casing.