A lighting circuit, which is configured to receive power from an alternating-current power supply via a dimmer to light a plurality of LEDs, the lighting circuit comprising: a rectification circuit configured to be connected to the dimmer and configured to provide pulsating voltage output depending on a dimming level set by the dimmer; a capacitance for smoothing the pulsating voltage output to form a direct voltage; a second switching element (D7, Tr1) that receives the direct voltage; a switching power supply unit connected between the rectification circuit and the plurality of LEDs, the switching power supply unit including a first switching element; characterized in a control circuit that receives the direct voltage via the second switching element and that is configured to use the direct voltage as a dimming signal indicative of the dimming level set by the dimmer, the control circuit further being connected to the first switching element and configured to perform on-off control on the first switching element so as to adjust power to be supplied to the plurality of LEDs in correspondence with the direct voltage; wherein the second switching element is configured to let the direct voltage pass and thus cause the control circuit to perform the on-off control on the first switching element as long as the direct voltage is higher than a predetermined level, and configured to block the direct voltage and thus cause the control circuit to stop performing the on-off control on the first switching element as long as the direct voltage is equal to or lower than the predetermined level, such that no power is supplied to the plurality of LEDs as long as the direct voltage is equal to or lower than the predetermined level. a rectification circuit configured to be connected to the dimmer and configured to provide pulsating voltage output depending on a dimming level set by the dimmer; a capacitance for smoothing the pulsating voltage output to form a direct voltage; a second switching element (D7, Tr1) that receives the direct voltage; a switching power supply unit connected between the rectification circuit and the plurality of LEDs, the switching power supply unit including a first switching element; characterized in a control circuit that receives the direct voltage via the second switching element and that is configured to use the direct voltage as a dimming signal indicative of the dimming level set by the dimmer, the control circuit further being connected to the first switching element and configured to perform on-off control on the first switching element so as to adjust power to be supplied to the plurality of LEDs in correspondence with the direct voltage; wherein the second switching element is configured to let the direct voltage pass and thus cause the control circuit to perform the on-off control on the first switching element as long as the direct voltage is higher than a predetermined level, and configured to block the direct voltage and thus cause the control circuit to stop performing the on-off control on the first switching element as long as the direct voltage is equal to or lower than the predetermined level, such that no power is supplied to the plurality of LEDs as long as the direct voltage is equal to or lower than the predetermined level.