A control-mode switching device includes: a plurality of actuators (2, 6, 7) that conduct different movement; driving means (10, 11, 12, 13, 14, 15) that drive the actuators; a plurality of control levers (22a-22c) that command operation of the driving means; a plurality of limit switches (72a-72e) that detect arrival of the control levers to the proximity of an end of a control range; a mode judging means (controller 23) that judges whether a priority operation mode is taken or not in accordance with a combination of on/off conditions of the limit switches; and a drive controlling means (controller 23) that, when it is judged by the mode judging means that the priority operation mode is taken, controls the driving means so that an output of selected one or more of the driving means becomes larger than that in a normal mode or the power ratio as compared with the other driving means becomes larger.