Current detection device

A current detection device used for a plurality of rotating electric machines (2,3,4;42,43) is provided. The rotating electric machines (2,3,4;42,43) are supplied with a composite current (I1-I12;I1-I9) containing a plurality of frequency components (F1,F2,F3,F4) from an single inverter (7) and the frequency is set in response to the rotational angular velocity of one rotating electric machine. The current detection device is provided with a current sensor (31,32,33; 51,52,53) which detects only current components at a single frequency in the composite current. The current sensor (31,32,33; 51,52,53) detects the currents in a set of supply lines (111,114,117;11,14), the supply lines of which being collected and passing through the current sensor (31,32,33; 51,52,53) so that the current components (Ia,Ib; Ic,Id; Ie,If; Ik,Il,Im of the frequency (F2;F4) different from the single frequency cancel out to zero in the set of supply lines (111,114,117;11,14).