PURPOSE: To adjust the focus and zoom of the projector neither manually nor manual operation through remote control.

CONSTITUTION: A recognition pattern is projected on a screen and the luminance of the recognition pattern is measured by a detection sensor 7 to calculate a contrast value; and the variation of the focus value of a projection lens and the calculation of the contrast value are repeated until the contrast value becomes maximum. When the contrast value becomes maximum, it is judged whether or not the recognition pattern is projected on the screen at a maximum, and when not, the zoom value of the projection lens is varied and the adjusting operation is redone from the calculation of the contrast value where the luminance of the recognition pattern is measured and ended when the recognition pattern is projected on the screen at its maximum.