Lighting circuit and luminaire

摘要

According to one embodiment, a lighting circuit includes a first power supply circuit (9), a first detecting circuit (11), a first control circuit (12), and a first protecting circuit (13). The first power supply circuit (9) is supplied with power from a first power supply (6) and outputs a direct current. The first detecting circuit (11) detects an electric current flowing between the first power supply circuit (9) and an output terminal. The first control circuit (12) compares a first detection value detected by the first detecting circuit (11) with a reference value and controls the first power supply circuit (9). The first protecting circuit (13) is connected to the first detecting circuit (11) and suppresses the first detection value detected if an electric current flows in a direction opposite to a first direction, which is a direction of the direct current output from the first power supply circuit (9), to be relatively smaller than the first detection value detected if an electric current flows in the first direction.