A switching control circuit is provided which can increase the off period of a switching element when the on period of the switching element is equal to the sum of the minimum pulse period (blanking period (a fixed period during which drain current is not detected after the switching element is turned on)) and a detection delay period (a period from when the drain current is equal to or higher than a detection criterion to when the switching element is actually turned off) and PWM control is disabled. An off period adjusting circuit generates, when the on period of the switching element is equal to the minimum pulse period, an adjusting signal OFF_C for increasing the off period of the switching element and supplies the signal to an on/off circuit for controlling the periodic on/off operation of the switching element.