An abnormality detection device is disclosed that includes a storage unit configured to, when abnormality of an in-vehicle device is detected, store abnormality information of the abnormality; a transmission unit configured to transmit the abnormality information to a server; an in-vehicle information terminal configured to, when driving support information is provided to an occupant and read-out operation information is input through an operation section, read out the abnormality information stored in the storage unit; and a transmission prevention unit configured to, when the read-out operation information is input through the operation section, prevent transmission of the abnormality information to the server.