To obtain an information processor which can easily be used even while being carried by detecting an angle component in a plane parallel to a display surface when the display surface changes its attitude, and rotating image information in parallel to the display surface according to the detection result of the angle component and controlling the display direction of the image information.

A personal computer 1 inputs detection data on an angular speed on an X axis from an input interface 60 by a CPU 30 in specific operation cycles and detects the angle of rotation of a display part 3 on the X axis on the basis of the angular speed detection data. The CPU 30 once detecting the display part 3 having changed its attitude according to the detected angle of rotation on the X axis and up-down and right-left rotational angle ranges changes the display direction by rotating a multiwindow picture displayed on a liquid crystal panel 7 according to the detected angle of rotation on the X axis. The display part can be viewed in a correct direction even in a train or the like during portage without any special operation.