A power supply control apparatus includes: a semiconductor switching element (6) configured to be switched with PWM control; a PWM signal output unit (1) configured to output a PWM signal pertaining to the PWM control; a current circuit (5) configured to output a current related to a current flowing through the semiconductor switching element (6); a filter circuit (11 to 13) configured to convert the current that is output from the current circuit (5) to a voltage and to filter the converted voltage; an overcurrent protection circuit (4) configured to turn off the semiconductor switching element (6) based on a voltage value of the voltage filtered by the filter circuit (11); a voltage detection unit(2) configured to detect the voltage value of the voltage filtered by the filter circuit (11 to 13) at a timing near an end of a pulse of a PWM signal; a temperature estimation unit (1) configured to estimate, based on the voltage value detected by the voltage detection unit (2), a temperature of an electric wire through which a current flows that also flows through the semiconductor switching element (6); and an electric wire protection unit (1) configured to turn off the semiconductor switching element (6) based on the temperature estimated by the temperature estimation unit (1).