Abstract: A optical flow-meter device comprises an outer tubular body provided with an inlet pipe fitting and an outlet pipe fitting for a fluid, and a tubular element made of transparent plastic material, which sealingly extends inside the body between the inlet and the outlet pipe fittings. The outer tubular body has two facingly arranged side openings for the insertion of a light-emitting element, and a light-receiving element connected to an electronic flow control and digital reading unit. A light-shuttering member is axially slidable within the inner tubular element and is shaped to allow the fluid to flow and at the same time to partialize or gradually shutter the light beam between the emitter and the receiver, providing an electronic signal proportional to the fluid flow running along the inner tubular element. A biasing spring member acts on the light-shuttering member to balance the fluid thrust.