Abstract: Locking device for crossings with movable frog point, including a cradle support with a central recess into which a movable frog point with transverse displacement in order to place thereof in two steady end positions is housed; characterized in that it comprises a pair of side left (10) and right (11) boxes, a transverse slide (9) through central part of which is connected to a movable frog point (8) being coupled in said side boxes (10-11), a widger (14) axial displacement of which carries the transverse slide (9) being guided inside said transverse slide (9), the widger (14) further comprising some depressions (30) into which the bottom of the locking rollers (25) is housed during the relative displacement of the widger (14) with respect to the transverse slide (9) and also during the whole movement of both elements (9-14).