The invention relates to a solenoid valve including an electromagnet (17, 4, 3, 10) made of a flat movable core (10), a fixed core (3) and a coil (17), the solenoid valve comprising a body (4) which also belongs to the electromagnet and includes an opening (23) located at the rear of the body (4), opposite the supply opening (18), for inserting the flat movable core (10), the fixed core (3) and the coil (17). The body (4) is secured to a retaining ring (8) made of a non-magnetic material, a flat spring (9) being compressed between the retaining ring (8) and the flat movable core (10).