To hold data at the moment a memory card is extracted by latching the data in response to a change of a card detection signal if the memory card is extracted by mistake.

A latch circuit 23 is provided to latch the data of the memory card 21 in response to a change of the CD(card detection) signal if the memory card is extracted by mistake while a main body reads in the data. Namely, if the memory card 21 is extracted, a CD signal pin goes up to 'Hi' after being unsettled (chattering) momentarily. The data which are being read are latched by the latch circuit 23 in response to a rise of the CD signal to 'Hi'. Then a data bus A after being unsettled (chattering) momentarily reaches 'Hi-Z', but a data bus B is already latched, so the data which are being read are guaranteed.