PURPOSE: To improve rigidity by a method wherein, in a handle securing device the angle of mounting to a power agricultural machine body of which is varied, a lock lever is engaged astride a space between a guide part formed to the bottom plate of a hand frame and a wedge-shaped notch part formed in a mounting bed seat.

CONSTITUTION: With a handle lock arm 7 rotated upward, a lock lever 6 secured on a rotary shaft 5 is separated from a notch part 16 of a mounting bed seat 12 and a guide part 28, formed to a bottom plate 18 of a hand frame 4, and a hand frame 4 is brought into a state in which it is rotatable based on a mission case 3. With this state, the hand frame 4 is rotated to a desired angle position. After some one of notch parts 16... is caused to coincide with a guide part 28 in the desired angle position, the handle lock arm 7 is rotated downward. In which case, the lock lever 6 is insertedly engaged with the guide part 28 and the notch part 16 and since the lock lever 6 is formed in the shape of a wedge, engagement having no clearance is practicable.