To provide an accessory for securing the safety of the infant, pupils, the aged, and the weak who are going tyo get on a vehicle.

A child seat is formed in a thin plate (Fig. 1 Base for vehicle seat) in such a way that fast attachment to the vehicle seat is ensured (Figs. 3-6 Function). The uses and functions of the surface of child seat are decomposed into unit functions (Fig. 19) and hook holders are mounted (Figs. 15-20) to be used as the accessory, and by replacing them frequently, protection of the infant, pupils, the aged, and the weak as well as effective use of inside the vehicle are established.