A current sensor includes semi-annular first and second magnetic cores, first and second sensors, and a differential output part. The first magnetic core is provided around a wire in which an electric current flows and includes a pair of first magnetic core parts each having a quarter annular shape. The first sensor is provided in the gap between the first magnetic core parts and detects a magnetic flux. The second magnetic core is provided around the wire and includes a pair of second magnetic core parts each having a quarter annular shape. The first and second magnetic cores form an annular magnetic core. The second sensor is provided in the gap between the second magnetic core parts and detects a magnetic flux. The differential output part outputs the differential output of the outputs of the first and second sensors.