This paper is aim to clarify the relation between a landowner and a conversion method in the conversion process of the un-intensive & unused land into pocket park, and to clarify an effect and a problem of having converted such land into pocket park in Adachi-ku. The administration appeals to the landowner for offer of un-intensive & unused land actively, and is undertaking the project secure such land as a pocket park site. It is cleared that Petit-Terrace system has the effect complemented in the arrangement of the park in a built-up area by consulting a map and questionnaire, and that conversion methods differ according to the category of landowner such as individual, corporation and administration, and management organizations differ according to conversion methods by interview to the person in charge. When an un-intensive & unused land is converted into pocket park by inhabitant's suggestion such as a part of the community design activities, it comes to manage by the organization, which can cope with the problem to generate flexibly. It was examined that defining the role of Petit-Terrace in the whole area was the effective means to cope with various problems after conversion.