To provide a vehicular radiator cooling fan control device for surely preventing a short circuit on a circuit, minimizing kinds of parts and reducing a cost.

A fan motor circuit of this radiator cooling fan control device comprises a first relay 2 having one (a) contact point 2a actuated by a first signal from the control device 1, a second relay 3 having one (a) contact point 3a actuated by a second signal from the control device1, a third relay 4 having one (a) contact point 4a actuated by the second signal from the control device 1, a first fan motor 5 of a sub-cooling fan and a second fan motor 6 of a main cooling fan. A preset time lag is arranged for sufficiently switching the respective contact points 2a, 3a and 4a of the three relays 2, 3 and 4 when switching the first signal and the second signal from the control device 1 to OFF from ON or when switching the signals to ON from OFF.