A manually-operated paint spray gun includes a body having a nozzle for atomizing paint to be sprayed and a handle forming a handgrip and provided with a connector for the inflow of compressed air to be supplied to the nozzle, wherein the handle of the gun has a compressed air regulator operatively associated to which is a pressure sensor at least part of which is arranged in a removable portion of the handle forming a substantial part of the dorsal area of the handgrip and is separated from the inflow connector.