third stop position mark 34 c shown in fig1 correspond respectively to the first stop position sa the second stop position sb and the third stop position sc actually the input means 51 may alternatively be configured so that the working device 4 is moved to the desired stop position the position angle is memorized and the stop position is adjusted the adjustment of the stop angle with the adjustment button group 65 or the slide bar 66 shown in fig4 may alternatively be used together therewith namely a user operates the operation levers 21 and 22 and adjusts visually the stop position of the arm 11 and evaluates the stop position as the stop angle with the position sensor 11 b so as to reflect it to the adjusted first stop angle a 1 displayed in the item 63 of the new set value according to the configuration for example at the first stop position sa the arm 11 is moved actually and evaluated as the first stop angle a 1 and at the step s 14 shown in fig5 the input means 51 judges whether the first stop angle a 1 which is evaluated by moving actually the arm 11 is within the adjustable range or not namely the input means 51 performs the judgement so as to realize a relation of the minimum stop angle x set previously u2266.