Three experiments on mental rotation were carried out to investigate conditions under which hand images are operated kinesthetically. In Experiment 1a, either a left or right hand was presented in a photographic slide, and subjects' task was left-right identification. In Exp. 2, each slide consisted of two hands, identical hands or mirror-imaged hands, and same-different judgment was required. In Exp. 3, two hands were presented successively, requiring same-different (mirror-reversed) judgment. On the other hand, subjects in Exp. 1b were asked to rate physical difficulty of actual hand movements to imitate stimuli. Six to 12 undergraduate students served as subjects in each experiment. The results suggested that subjects' mental operations of hand images were kinesthetic in Exp. 1a but visual in Exp. 2 and 3, on the basis of comparison between reaction times in the three experiments and the ratings in Exp. 1b. Conditions which give rise to kinesthetic image processes were argued in relation with task structures.