The purpose of this research was to develop an automated harvesting system for hard clams (Meretrix lusoria) that can be operated by one person to reduce labor requirements and costs. The automated harvesting system consists of a driving vehicle and an automatic harvesting device, both of which passed through three phases of development. The driving vehicle has a pair of rod wheels so that it can be navigated in the water by a single operator on the vehicle. It was modified from a simple single-wheeled raft which has to be operated by a person who walks behind it. The direction of movement of the driving vehicle is changed by braking with the right or left rod wheel using an agricultural gearbox. The automatic harvesting device is composed of a traditional clam-collecting cage and a conveyor, which can be powered by its own engine or by the diesel engine on the driving vehicle. In order to reduce the total length of the system, an amphibious vehicle was developed which contains a conveyor run by the diesel engine of the vehicle. The water pump of the collection device is run by another diesel engine on a raft in front of the vehicle. The diesel engine has a power rating twice as high as traditional harvesting devices to enhance the pumping energy. Due to the increased weight of the diesel engine, it is loaded on a raft which is pushed by the amphibious vehicle while the collection device is dragged behind the raft. Preliminary tests showed that the amphibious vehicle and the harvesting device can easily be moved up and down the ramp of the pond and can effectively harvest clams.