A lighting device control apparatus used in a vehicle which includes a headlight for illuminating a running direction of the vehicle; a first lighting device provided at a side of an external mirror of the vehicle; a second lighting device provided at a front side of the external mirror; and a direction indicator operating device, operated by a driver of the vehicle, for indicating the running direction of the vehicle, wherein the direction indicator operating device controls at least the on/off state of the first lighting device. The apparatus has a lighting device control device for producing a daytime on-state of the second lighting device, according to an on state of the headlight and an operational position of an ignition switch of the vehicle. The second lighting device, conventionally used as a direction indicator, can be used as a daytime running light for improving the visibility in the daytime.