A delivery assistance device assists in an operation of a delivery service in which a vehicle cabin including a trunk of a vehicle used by a requester is able to be designated as a luggage delivery destination. The delivery assistance device includes a key information distribution unit configured to distribute key information that a deliverer of a company that provides the delivery service is to use to unlock a door for access to the vehicle cabin of the vehicle, to the company, and an entry authority information distribution unit configured to distribute entry authority information regarding an authority for the deliverer to enter a predetermined area in which the vehicle is present, to the company when the key information is distributed to the company by the key information distribution unit.