IN-VEHICLE POWER SUPPLY DEVICE

An in-vehicle power supply device is used in an in-vehicle power supply system The in-vehicle power supply system includes a battery a power path to which power based on the battery is supplied, and a capacitor electrically connected to the power path The in-vehicle power supply device includes a first circuit (e.g., a precharge circuit and a second circuit (e.g., a relay circuit The first circuit (e.g., the precharge circuit performs a precharge operation of precharging the capacitor. The second circuit (e.g., the relay circuit has a configuration in which a plurality of relays (e.g., first relays are connected in parallel, and is provided on the power path closer to the battery than is the capacitor