Abstract: A computer system comprises a computer body that is attachable to a user's body. A projection port is formed in the outer surface of a housing of the computer body. The housing contains therein a display element that projects an image outward from the housing through the projection port. The housing further contains therein a vibration detecting element for detecting vibration of the computer body, a discriminating element for determining whether or not the computer body is moving, in accordance with a vibration pattern detected by means of the vibration detecting element, and a main control element adapted to stop the image display by means of the display element when it is concluded by the discriminating element that the computer body is moving.