This utility type patent publishes a safety control device for petrol post hold digger. It includes an operation frame, respective handles in the opposite two sides of the frame; one is throttle control handle in the right side and another is balance control handle in the left side. The safety control device is mounted on the above of the frame near left side, connected with engine in the middle place of the operation frame by one cable, with the throttle control handle in the right side by another cable. A long touch rod is installed underneath the safety control device, sticking outside of the operation frame to position A as shown in bellow picture.When post hole digger is used, drill bit is driven into soul at clockwise direction. If the drill bit touches big roots or rocks and stops rotation in a sudden, all the inertia and torque from still running engine will be thrown to the operation frame, makes it turn to opposite anticlockwise direction. Then the touch rod, usually sticking out of the frame at position A, will turn to touch leg and rotate in a certain angle towards position B. Detecting this angle change, the safety control device will act and reduce the engine torque by releasing its throttle cable to get a lower speed. As a result, to avoid the operator's danger of falling down, make the machine always operate under comfortable control.This patent is designed to be safe in operation, simple in structure and high practical in use.