The present invention is directed to solve a problem that time is required for a process related to verification of a public key certificate of a message sender. An in-vehicle device mounted on a vehicle has a memory for holding information of a device which failed in verification of a public key certificate. At the time of performing communication between vehicles or between a vehicle and a roadside device, a check is made to see whether or not information of a device included in a message transmitted matches information of a device which failed and held in the memory. When the information matches, verification of a public key certificate is not performed.