A vehicle guidance system includes a hardware processor. The hardware processor specifies, outside a vehicle, a route from a starting position to a target position in a parking lot, and transmits, to the vehicle over a communication network, information about at least one route section of the route. The hardware processor determines detection accuracy of a first monitoring device being set as an active monitoring device out of monitoring devices. The active monitoring device serves to monitor deviation of the vehicle from the route section during autonomous driving along the route section. In response to determining that the detection accuracy of the first monitoring device is lower than a reference accuracy, the hardware processor sets a second monitoring device as the active monitoring device in place of the first monitoring device. The second monitoring device is different from the first monitoring device among the monitoring devices.