IN-VEHICLE DEVICE, TIME SYNCHRONIZATION METHOD, AND TIME SYNCHRONIZATION PROGRAM

An in-vehicle device includes: a processing unit configured to perform time synchronization between own device, which is the in-vehicle device, and another device, which is another in-vehicle device, based on a data propagation delay time between the other device and the own device, and detect occurrence of an update event regarding the propagation delay time, wherein in a case where the processing unit detects occurrence of the update event, the processing unit requests time information used for updating the propagation delay time from the other device.