To provide a vehicular power control device capable of efficiently supplying stable D.C. power from a battery to a load circuit even at battery voltage drop.

A first diode 50 is connected to be set in a forward direction from a voltage input part M to the gate G of a P-channel FET element 10; a capacitor 60 is connected between the cathode and the gate G of the first diode 50; a switch means 20 connects the gate G to a ground GND to charge the capacitor 60 based on input of an operation signal; an impedance adjustment means 40 adjusts impedance of a path between the gate G and the ground GND connected by the switch means 20 to set the impedance in charging the capacitor 60 lower than that when the voltage V1 of a power source 200 drops by the beginning of the start of an engine 700.