There is provided a lighting circuit configured to drive a light emitting unit including a first light source and a second light source connected in series. The lighting circuit includes a first pin connected to one end of the first light source, a second pin connected to a connection node of the first light source and the second light source, a third pin connected to one end of the second light source, a drive circuit configured to supply a drive current to the light emitting unit, a bypass switch provided between the second pin and the third pin, a first resistor provided in parallel with the bypass switch between the second pin and the third pin, and an abnormality detection circuit configured to detect abnormality based on a detection voltage generated between the second pin and the third pin when an ON signal is applied to the bypass switch.