An eye muscle trainer has an outer casing, a control circuit module, a first light emitting unit set, two second light emitting unit sets, two third light emitting unit sets and an eye frame. The outer casing is opaque and has a rear opening. The light emitting unit sets are mounted on the control circuit module. The first light emitting unit set is for focusing user's vision. The second light emitting unit sets are for focusing user's vision on seeing straightly. The third light emitting units are for focusing the user's vision on seeing outwardly. The eye frame accommodates the rear opening of the outer casing. Therefore, wearing the eye muscle trainer releases eyestrain because watching the light emitting unit sets arranged at different position exercises the user's eyes. Consequently, appropriate releasing eyestrain assists improving eyesight.