The purpose of this study is to analyze the load on the PTO shaft and the power required during garlic harvester operation according to the depth at which Nanji and Hanji garlic, two varieties of Korean garlic, are harvested. In order to identify the need for developing a garlic harvester, we identified the deepening shortage of agricultural labor through the phenomenon of decreasing and aging agricultural population. Since the garlic harvester is driven by transmitting rotational power through the PTO shaft, we focused on the load on the PTO shaft and the power required. Before testing the garlic harvester, we measured the physical and mechanical properties of the soil by dividing it into Layer1 and Layer2 to understand the properties of the soil. Then, we analyzed the soil properties and found that the soil was a sandy loam. The experimental conditions were divided into eight conditions based on the depth at which Nanji and Hanji garlic are harvested, the rotation speed of the PTO shaft, and the travel speed of the tractor. The load of the PTO shaft and the power required were analyzed by finding the working section in each experimental condition. The condition with the largest PTO shaft load and the largest power required in sandy loam soil was P2L2D10. The PTO torque was 237.903 Nm and the average PTO power was 2.380 kW. This means that 22.05% of the tractor’s rated power of 42 kW was required, and the average power required was about 5.79 times higher than that of P1L2D5, the condition with the smallest power requirement. Therefore, it can be seen that care must be taken in garlic harvesting operations as the working depth increases.