This study aimed to develop models for estimating the physical load on elderly individuals with reduced physical function during assisted walking. Five models were constructed, considering the participants’ body balance, walking stability, posture comfort during assisted walking, and total pressure on both feet. In this study, assistive products for walking, as a category of welfare aids, were the primary focus. The optimal placement of such aids in actual caregiving settings was assumed as the “optimal solution”, and the validity of each model was verified by comparing the “optimal aid placement positions” calculated by each model. Two definitions were adopted for determining the optimal aid placement positions: (1) the location where the area of reduced load due to the aid installation was most significant, and (2) the location where the total reduction in load due to the aid installation was most significant. As a result, under definition (2), the model considering body balance and walking stability was considered valid, resulting in the shortest distance between the “optimal solution” and the calculated “optimal aid placement position.”