To solve the problem that a living action range of the elderly who do not have suitable moving means other than walking has to be limited since in spite of the fact that a bicycle is handy moving means for the elderly, there is a risk of overturning while a walking aid vehicle is indispensable for the elderly going shopping for daily necessaries.

A folding-type four-wheel bicycle is usually used as safe moving means for the elderly as a four-wheel bicycle with no risk of overturning, and when folded, can be used as a walking aid vehicle with which the elderly can walk safely, and which is convenient for shopping, thereby connecting different moving actions of walking and bicycle riding in a quick manner, and solving the problem that a living action range of the elderly becomes limited.