[出版社版] ; There are a lot of people who point out uneasiness to the appearance that the grade- chooler plays with the friend. It is because it tends to become a one-sided relation of attacking the other party well in the self-control, and it is difficult to underst mutually. “Companion” is the one that the age is in the vicinity, the body, psychologically, and socially in a similar standpoint with oneself. It is said that mutual negotiation with the companion will play a major role for the children’s social development. The purpose of this research is to do the observation investigation of the four-years old children who begins to be actively related with the companion, and to clarify the developing process of the peer relationship. It is based, and the suggestion of the development of child’s interpersonal relationship in the puerility and youth is obtained. The feature of the process of formation of four-years old child’s peer relationship is as follows. 1)They feel goodness that play with the friend. 2) They conflicts with friend. 3) They concentrate on their play. 4) They notice the charm of the friend. 5) They want to be admitted.