lc is eliminated a normal driving current is sequentially fed to each of the stator coils at a normal timing in the aforementioned embodiment the two input and gate and2 generates a logic 34 1 34 when the external noise affects the three phase logic lc and the driving signals are simultaneously output from the first phase and second phase output terminals u03c61 and u03c62 of the three phase logic lc similarly in the case that the second phase output terminal u03c62 of the three phase logic lc is a normal driving signal output terminal and that an abnormal driving signal is output from the third phase output terminal u03c63 the two input and gate and3 generates a logic 34 1 34 further in the case that the third phase output terminal u03c63 is a normal driving signal output terminal and that an abnormal signal is output from the first phase output terminal u03c61 the two input and gate and1 generates a logic 34 1 34 as a result the transistors tr1 tr2 and tr3 are turned off in each case as mentioned above referring next to fig2 which shows an alternative embodiment of the present invention an abnormal driving current cut off circuit sfc2 is provided in the same manner as an abnormal driving current cut off circuit sfc1 in the foregoing preferred embodiment output terminals u03c61 u03c62 and u03c63 of the three phase logic lc are connected to input terminals of two input and gates and1 and2 and and3 respectively output terminals of the two input and gates and1 and2 and and3 are connected to input terminals of three input or gate or an output terminal of the three input or gate or is.