Provided is a power supply device for a lighting device for a vehicle composed of a plurality of unit lighting modules which is easy to install and disassemble due to excellent assembly capabilities, and which stably supplies power with excellent connection stability. In the power supply device for supplying power to the lighting device for the vehicle composed of a plurality of unit lighting module, the power supply device includes: a connection rail member provided in each unit lighting module to supply power to a PCB of the unit lighting module; and a connection pin member electrically coupled to the connection rail member in a male and female manner to electrically connect two adjacent power supply modules to each other.