To provide a technique of facilitating the countermeasure in occurrence of abnormality.

A projector apparatus has input signal terminals (A)1, (B)1b, a signal processing section 2, a display device section 3, an operation section 4, a controller 5, a storage section 6 and a network controller 7. The memory section 6 is provided with a processing program 6a, and the network processing section 7 is provided with a LAN interface 7a. When a signal is input to a signal input terminal 1, the kind determination of the signal and the signal processing optimum for the display device 3 is performed in the signal processing section 2 and the projection to the screen from the display device 2 is performed. Also, when the key operation of the controller is performed, the controller 5 records the content of the key operation in the storage section 6, reads the data from the storage section 6 by the key operation, controls the signal processing section and records the result thereof in the storage section 6.