To quickly and accurately select a mark which meets a user's will.

This device includes a sight line detecting means for detecting the position of a user's sight line within an observation plane; marks L2, L1, C, R1 and R2 provided within the observation plane for directing the start of desired action according to the user's sight line; and a selecting means having a plurality of first judging ranges EYL2, EYL1, EYC, EYR1 and EYR2 and a second judging range EYBN at boundaries to the plurality of first judging ranges, for selecting at least one of the plurality of marks if the position of the sight line detected by the detecting means is not contained in the second judging range but in either of the first judging ranges, and for selecting a mark according to the result of re-detection of the sight line by the detecting means if the position of the sight line is contained within the second judging range.