This research aimed to examine whether early discharge can be performed by nurses of a ward participating in the process of critical path method supporting with offer and evaluation of standard and efficient medical treatments and nursing cares. In order to enrich the system that performs hospitable medical treatment and nursing cares standardized at the psychiatry acute term and to prevent chronic, critical path method was introduced into the acute term ward, then the investigation for nursing job satisfaction that was important to establish critical path method was conducted. By introducing critical path method, it became possible to assess the patients in standard, and the subject of business or a system became clear towards early discharge. It became possible to tie up this subject to a future improvement. Consequently, as for comparison of the patient who applied the schedule table of critical path method at the first and second term, the latter decreased the average length of hospitalization period significantly. The satisfaction of the task requirement, which was important to maintain systems, was decreased by the introduction of critical path method but the score of autonomy in satisfaction increased significantly by the improvement of usage of critical path method. From these, it was suggested that the introduction of critical path method in the acute-care unit psychiatry had possibility to aim at standardization of treatment and nursing and patients' early discharge from hospitals.