Connection normality check of a pair of electric wires is simplified. A circuit check device 1 that checks connection normality of a pair of electric wires L1 and L2 includes, when the pair of electric wires is connected to an exchange 2, a voltmeter 11 that measures a first inter-wire potential difference between one end of an electric wire portion p1 of the electric wire L1 and one end of an electric wire portion p2 of the electric wire L2, a voltmeter 12 that measures a second inter-wire potential difference between the other end of the electric wire portion p1 of the electric wire L1 and the other end of the electric wire portion p2 of the electric wire L2, and a determiner 13 that determines whether the measured first inter-wire potential difference agrees with the measured second inter-wire potential difference.