A driving circuit for a four phases (1, 2, 3, 4) step motor, where each stable rotor position is reached by suitably energizing the series of two of the four phases, comprises a circuit (22) which controls the current in the energized phases by comparing a current related signal with a reference signal. Particularly, such circuit disconnects the series of two phases from the power supply and ground when the energization current reaches a predetermined upper threshold value and connect it again to the power supply and ground when the energization current, which is maintained in the phases through recycle diodes (9, 10, 11, 12), falls below a predetermined lower threshold value. In such way the energization current within the phases is kept nearly constant and this reduces to a minimum the winding copper losses, under the same mechanical performances. The cross configuration of the windings, with a current sensor (19) in the center of the cross, further enables to reduce to a minimum number the components of the control circuits.