PURPOSE: To automate a reader posture control operation which corrects vertical postures of a reader with the aid of a computer without depending on an operator since an operator may turn over a pile driver by his poor handling.

CONSTITUTION: This reader posture control device provides a reader-every- direction inclination sensor 1 and a computer 4 which processes a signal from the sensor 1 where the computer 4 reads every direction of the reader's inclination angle from the reader-every-direction inclination sensor 1 and calculates the expansion direction of stay cylinders (b) on both sides in order to set vertically a reader (a) and transmits signals to change-over valves 7 and 8 which control the stay cylinders (b) on both sides and expands and contracts the both sided cylinders (b). Furthermore, there is installed a main body-every-direction inclination sensor 2. The computer 4 reads each inclination angle from the reader-every-direction inclination sensor 1 and the main body-every-direction inclination sensor 2 and gives an alarm to an alarm device 3 when an operational failure is detected and halts an emergency operation.