A switching power supply device includes an energy storage element which is charged with a voltage generated in an auxiliary winding of a transformer; a switching control circuit to which the terminal voltage of the energy storage element is given as a power supply voltage and which controls the switching operation of a switching element; an initial operation control circuit which, when it is detected that the power supply voltage is lower than a first voltage, causes a current supply circuit to stop the switching operation until the power supply voltage rises to a second voltage; and a switching suppression circuit which, when it is detected that the power supply voltage is lower than a third voltage which is higher than the first voltage and lower than the second voltage, causes the current supply circuit to stop the switching operation for a predetermined period.