A dispensing device for granular or powdered materials, comprising: a main body (200); a dispensing channel (2a), arranged at least partially in the main body (200) and provided with a longitudinal axis (X), an inlet opening (21) and an outlet opening (22); a suction means, provided to retain, upon command, at least a part of granular or powdered material inside the dispensing channel (2a), so as to form an accumulation that obstructs the dispensing channel (2a) and prevents the flow of material; at least one suction opening (23), placed in communication with the dispensing channel (2a) and with the suction means; a filter (20), interposed between the suction opening (23) and the dispensing channel (2a); a ventilation portion (20b), associated with the main body (200) and connected to the inlet opening (21), which is provided with an outer surface (20d) placed in communication with an environment at a determined pressure.