PROBLEM TO BE SOLVED: To prevent a lighting device from erroneously outputting power for light source lighting when a light source module is not connected.SOLUTION: A step-down chopper circuit 41 turns on/off a switching element Q1 to regulate a voltage of power supplied from a step-up chopper circuit 31 to a predetermined voltage. A connection detection determination IC 52 determines whether an LED module 12 is connected to the step-down chopper circuit 41 on the basis of a voltage output from a parallel circuit of a smoothing capacitor C1 and a resistor RP. A step-down chopper control IC 42 turns on/off the switching element Q1 of the step-down chopper circuit 41 when a predetermined period elapses after the start of power supply from the step-up chopper circuit 31 and if the connection detection determination IC 52 determines that the LED module 12 having a resistor RL for connection detection is connected to the step-down chopper circuit 41.
