Control device, vehicle lamp system, and vehicle lamp

A control device (50) includes an image detecting section (52) configured to receive image data of an image taken in front of a vehicle, and to detect the average brightness and the number of light spots of the image on the basis of the image data, an irradiation determination section (54) configured to determine an irradiation control method to be used for a vehicle lamp (70) based on both the brightness and the number of light spots, and an output section (58) configured to output a control signal to the vehicle lamp (70) so that the determined irradiation control method is performed.