A vehicle lamp comprises a light source, a drive circuit, a CPU, and a gradual varying controller. The drive circuit supplies a driving current to a light source according to a dimming signal. The CPU generates a turn on or off ordering signal that instructs the light source to be turned on or off according to an instruction from a vehicle and information that indicates a driving situation. The gradual varying controller generates the dimming signal that varies gradually with time in response to the turn on or off ordering signal. The vehicle lamp can be switched between a first mode in which the light source is turned off momentarily and a second mode in which the light source is turned off gradually.