Aims & Objectives: In order to create the best environment for a psychiatric treatment facility, it is important to understand how psychiatric patients recognize their environment and what factors influence their cognition. In this study, we try to find out the essential features in a physical environment that could influence the well being of the patients by examining the spatial preference and environmental behavior of patients with varied psychiatric illnesses. Context & background literature: The relationship between the staff area and the patients’ private area is the key factor in designing the structure and the environmental characteristics of ward spaces in a psychiatric hospital. Recent research has found that for the purpose of treatment and securing privacy, psychiatric patients need to be in an open space of relief rather than closed confined environment and under the watch of nursing staffs. It is considered that the characteristic of spaces in psychiatric ward is closely related to relationship between nursing staffs and patients and psychological territories that they possess. Thus, the characteristics of spaces in a psychiatric ward, which arise from psychological dominant structure, are closely related to the environment of treatment and relief for psychiatric patients.Method of inquiry or argument: We conducted a survey at three kinds of wards in a private psychiatric hospital in Japan in October 2002. These wards include an acute ward, a psychiatric convalescence ward, and a stress care ward. All three kinds of wards have the same structure. At each ward, spatial preferences of the 145 psychiatric inpatients were surveyed and data concerning the patients diagnostic category, symptoms, and activities of daily living were recorded.Findings & Conclusions: The patients in the stress care ward prefer to stay in private spaces than public spaces. On the other hand, in the acute ward the patients seem to have a preference between managed public spaces where are monitored by nursing staffs and their private rooms where the nurse station is close. In addition, the patients in the psychiatric convalescence ward spend most of their time in the public space, such as the hallways or the day room. Base on our research, we concluded that spaces that could be monitored by the nursing station serves effectively as a safety space for patients in the acute ward. However, in the stress care ward, the patients may perceive the monitoring by the nursing staff as interruption or nuisance to their relaxation. In order to design an ideal healing environment for psychiatric patients in psychiatric ward, it is important to consider how environmental characteristics of space affect the environmental sense of patients in each ward.