To automatically set a plurality of functions without making a user operate.

This device apparatus 100 is provided with a communication interface for communicating through a USB cable with a personal computer, liquid crystal integral tablets 104 and 106, a holding part 154 for holding a lower cover part 150 including the liquid crystal tablet 104 and an upper cover part 152 including the crystal liquid integral tablet 106, an opening/closing switch provided in the holding part 154 for detecting the open state of the upper cover part 152, and an MPU for deciding the operation mode of the device apparatus 100 based on the communication validity/invalidity with the personal computer judged by the communication interface and the display validity/invalidity of the liquid crystal integral tablet detected by the opening/closing switch.