In a switching regulator control circuit according to aspects of the invention, a drain current is converted to a voltage Vis with a resistance. The voltage is delivered to a multiplication circuit. The multiplication circuit generates and outputs a voltage that is a product signal of the voltage and a voltage that is proportional to a duty factor. A comparator circuit compares the voltage with an error signal delivered to the other comparison input terminal of the comparator. When the voltage has reached the error voltage, the comparator delivers a turn-off instruction through an OR circuit to a terminal of a flip-flop.