The increasing average age of agricultural workers owing to the declining birth rate and aging population is becoming a serious problem worldwide. To harvest and transport products, it is necessary to lift, lower, and move containers when transporting them, but this work is a heavy burden not only for the elderly but also for young people. Thus, several electric assistive devices have been developed for carrying this load, including some in the field of long-term care. However, because of the complexity and high cost of the equipment, they are not widely used on private farms and in ordinary households. To solve these problems, we have developed a motorized auxiliary device for lifting and transporting goods. It has a simple structure, few failures, and low cost. Instead of conventional motors, hydraulics, or pneumatic pressure, the energy source for this device is the worker’s thigh muscles, which generate the greatest force in the human body. In addition, instead of using arm muscles to support the load, the device causes the load to be supported with the shoulders. In this study, we demonstrate the basic structure and mechanism of the device, analyze the dynamic characteristics of some mechanisms, and propose effective mechanical elements for lifting the load.