To provide a door unlocking device for a vehicle realizing a smart entry system capable of forming a remote control key into an arbitrary shape.

This door unlocking device for the vehicle loaded on the vehicle to release door lock is provided with an electric power supply means for supplying electric power to a portable machine (the remote control key) in the outside of the vehicle, a checking means for checking an ID code included in a signal transmitted from the portable machine receiving supply of electric power by the electric power supply means with a predetermined ID code, a door unlocking means for releasing the door lock when confirming agreement of both ID codes by the checking means, and a power generation means for generating electric power by manual operation to supply the generated electric power to the electric power supply means, the checking means, and the door unlocking means.