A semiconductor device includes external interface terminals and processing circuits, and it is fed with an operating power source when detachably set in a host equipment. Power source feeding terminals (VCC, VSS) among the external interface terminals are long enough to keep touching the corresponding terminals of the host equipment for, at least, a predetermined time period since the separation of an extraction detecting terminal among the external interface terminals, from the corresponding terminal of the host equipment, and they are formed to be longer in the extraction direction of the semiconductor device than the extraction detecting terminal. These power source feeding terminals are a power source terminal and a ground terminal, and any power source compensating capacitor is not connected between the power source terminal and the ground terminal. Since a time period required till the cutoff of the power source can be easily ensured, a capacitor for compensating the operating power source at the power source cutoff which occurs midway of an operation is not necessitated.