To provide a road information center, a program for computers, and a road information processing apparatus for providing a detour including minor streets.

A large number of vehicles 3A, 3B, etc. in which vehicle-mounted terminals are each onboard and user terminals NP such as notebook computers are connected to the road information center 1 via a network 2. The center 1 stores information on both main roads (for example, 31-35) and congestion of the main roads and minor streets (for example, 41-43) through which it is unknown whether vehicles are passable or not and provides the vehicles with, for example, a road map. When a specific vehicle (for example, the vehicle 3A) has requested of the center 1 a detour from a present location JP to a destination TG avoiding congested areas J1-J4, the center 1 acquires information as to whether vehicles are passable through narrow streets or not from the user terminals NP and provides the specific vehicle with a detour determined through the use of the narrow streets verified as passable for the vehicles as well. It is possible to input the sizes of vehicles passable through the narrow streets from the user terminals NP and to use only narrow streets passable for vehicles of the size of the specific vehicle or larger for determining the detour.