A light source control device is provided. A switching seat includes a switching key and a sensing device. A switching circuit is disposed between an external power source and a control circuit to disconnect or connect the external power source, and includes a mechanical switch, an electronic switch and a sensing unit. The mechanical switch is directly connected to the switching key, and is controlled to turn on or off by switching the switching key. The electronic switch is coupled to the sensing unit, and the sensing unit generates a sensing signal to control the electronic switch to turn on or off when the sensing device senses an excitation. The control circuit provides varied power supply to a light source according to the received signal.