PURPOSE: To provide a magnetic card device maintainable prior to writing and reading information by providing mechanism for monitoring the soil of a conveyor means in this magnetic card device for writing or reading information by a command inputted from an external device, with a magnetic card as a medium.

CONSTITUTION: A magnetic card device has a conveyor means 2 for conveying a magnetic card 1 into the specified position, and an optical sensor 7 for detecting the soil of the conveyor means 2. When the level of a signal outputted from the optical sensor 7 in correspondence with the soil exceeds the set value, an error signal is outputted from a control circuit 5 for controlling the conveyor means 2 or from an external device 6 connected to the control circuit 5.