A DC/DC converter comprising: a first switch and a second switch arranged in series between a first power source which supplies a first potential (Vdd) and a second power source which supplies a second potential (Vss) lower than the first potential (Vdd), the first switch being positioned closer to the first power source than the second switch; a switch control unit for controlling an on-off operation of the first and second switches (SW1, SW2); and said switch control unit turning off the first switch when the potential of an output node (Vnd) between the first switch and the second switch is below a first reference potential which becomes a reference to detect an occurrence of inrush current and excessive current while the first switch is in an ON state; wherein said switch control unit comprises: a first reference potential generating circuit for generating the first reference potential; a first potential comparator for comparing the first reference potential generated by the first reference potential generating circuit with the potential of said output node (Vnd); and an available period setting circuit for setting an available period during which comparison results of the first potential comparator is valid, said switch control unit turning off the first switch when the first potential comparator detects that the potential of said output node (Vnd) is below the first reference potential during said available period set by said available period setting circuit, wherein said available period setting circuit sets a start of said available period at a time when a predetermined time period has elapsed since the first switch is turned on. a first switch and a second switch arranged in series between a first power source which supplies a first potential (Vdd) and a second power source which supplies a second potential (Vss) lower than the first potential (Vdd), the first switch being positioned closer to the first power source than the second switch; a switch control unit for controlling an on-off operation of the first and second switches (SW1, SW2); and said switch control unit turning off the first switch when the potential of an output node (Vnd) between the first switch and the second switch is below a first reference potential which becomes a reference to detect an occurrence of inrush current and excessive current while the first switch is in an ON state; wherein said switch control unit comprises: a first reference potential generating circuit for generating the first reference potential; a first potential comparator for comparing the first reference potential generated by the first reference potential generating circuit with the potential of said output node (Vnd); and an available period setting circuit for setting an available period during which comparison results of the first potential comparator is valid, a first reference potential generating circuit for generating the first reference potential; a first potential comparator for comparing the first reference potential generated by the first reference potential generating circuit with the potential of said output node (Vnd); and an available period setting circuit for setting an available period during which comparison results of the first potential comparator is valid, said switch control unit turning off the first switch when the first potential comparator detects that the potential of said output node (Vnd) is below the first reference potential during said available period set by said available period setting circuit, wherein said available period setting circuit sets a start of said available period at a time when a predetermined time period has elapsed since the first switch is turned on.