Abstract: A spray gun with an automatic valve opening control means which enables remote and stepless control of a paint spraying operation has atomizing means provided at the front end thereof, a paint valve member which enables adjustment of the amount of paint jetted out from the atomizing means, and a spray pattern adjusting valve member adapted to adjust the spray pattern by controlling the amount of compressed air jetted out from the atomizing means. A threaded slider mechanism is provided on the proximal portion of a valve body of either the paint valve member or the spray pattern adjusting valve member (or both). A servo motor and an encoder are connected to a drive screw member of the threaded slider mechanism. The encoder is adapted to detect the rotational position of the servo motor and output a controlled variable of the motor, and the servo motor is controlled in response to an external signal.