Abstract: A portable hand held post driver which is fully operable by a single worker and which uses a fluid powered cylinder to drive posts into the ground. The cylinder raises a balanced driving weight and forces the weight down onto the post. The cylinder is reversed automatically at both the top and bottom of its stroke to automatically repeat the driving strokes so long as a hand lever is held by the operator. The post is clamped to the frame of the implement by a clamp having an overcenter control linkage. Before the implement can be operated, a safety linking pin must be intentionally released by operating a safety lever.