PURPOSE: To uniformly adjust the driving speed for a working member by installing an instruction value change setting means which calculates the difference between the operation speed obtained from the speed data and the actual operation speed supplied from a speed setting means, and set changedly the instruction value which is supplied to a fluid quantity adjusting means from a drive control means on the basis of the above-described difference.

CONSTITUTION: A turning-up/down operation quantity sensor 23 as operation quantity detecting means, a extension/contraction operation quantity sensor 24, a turning operation quantity sensor 25, and a traveling operation quantity sensor 26 detect the operation quantities of the respective levers 15 - 18, and output the signals corresponding to the operation quantity. Further, a turning-up/down angle sensor 21 and a boom length sensor 22 output signals corresponding to the detection value. A microcomputer 31 as a drive control means, a speed setting means, and an instruction value change setting means is constituted of a logic calculation circuit in which a central processing unit 32, a memory 33 used exclusively for read-out which previously memorizes the prescribed control programs, etc., an instruction value data memory means which temporarily memorizes the result of the calculation of a CPU 32, a multiplexor 27, an A/D converter 28, and input/output port 29, etc.