[PROBLEMS] To provide a magnetic head provided with a microprocessor capable of storing a firmware downloaded from an external server. [MEANS FOR SOLVING PROBLEMS] The magnetic head has a core which is provided with a coil for converting data stored in a magnetic card to analog signals, an A/D conversion chip which is connected to the core to convert the analog signals to digital signals, and the microprocessor which is connected to the A/D conversion chip. The processor has a firmware storage means. When the firmware which controls its arithmetic/storage functions and controls an external hardware is downloaded from the external server (11) to the magnetic head, the firmware storage means stores the firmware.