To effectively suppress the power consumption of a battery and to enable long-time use at the time of portage by providing a control part which perform ON/OFF control over battery while classifying a video display part by function blocks.

A microcomputer 1331 detects whether or not some operation is done for a certain time after the power unit 134 is turned by an electric or mechanical sensor or switch, etc., to turn off the power unit when no operation is done and turn on the power unit 134 when some operation is done thereafter. This control is carried out by one of combinations of four function blocks, i.e. A (only fluorescent lamp 132), B (fluorescent lamp 132 and two LCDs 118), C (fluorescent lamp 132, two LCDs 118, video signal processing circuit 1333), and D (fluorescent lamp 132, two LCDs 118, video signal processing circuit 1333 and microcomputer peripheral circuit 1332) or plural combinations according to a system in use.