PURPOSE: To obtain a controller having good operability for a blade by a method in which manual and automatic selection mode circuits are provided, and control commands during the automatic mode time and manual mode time are controlled by the same control means.

CONSTITUTION: A controller for a blade 1 is made up of an operation lever 19 to generate tilt and lift signals for the blade 1, means 100 and 200 to send out the signal of frequency corresponding to the value of the control signal, counters 106 and 206 to count the output signal of the operation lever 19 as a control signal generation means during the period when manual operation switches 15 and 28 are in operation, a mode selection circuit 300 to select automatic mode and manual mode of the signal showing the count content of the counter 106 and 206 and the control signal, and mode switch elements 15 and 28. The control commands at the time of automatic mode and manual mode can thus be made by the same commanding means.