Background/Purpose: The purpose of this study is to clarify the effectiveness of interventions for breast cancer patients with psychological distress by a clinical psychologist on the basis of the contents of the interventions and counseling. Methods: The participants were 20 inpatient and outpatient women aged from 33 to 73 years who had been diagnosed with breast cancer. The interventions were conducted on the basis of patients' complaints about anxiety and/or depression or by a medical doctor's request. The interventions employed unstructured, one-on-one interviews. Each interview usually lasted no more than 60 minutes. Results: The 20 cases were classified into the following categories: (1) 15 general (nonpsychiatric) cases, consisting of (1-1) 9 cases at the cancer-notification and progressive-therapeutic stages and (1-2) 6 cases at the progressive-relapse stage; and (2) 5 specific (psychiatric) cases, consisting of (2-1) 3 cases at the cancer-notification and progressive-therapeutic stages and (2-2) 2 cases at the progressive-relapsestage. As for the general cases, interventions were found to be effective in all 9 cases at the cancer-notification and progressive-therapeutic stages but in only 2 of 6 cases at the progressive-relapse stage. In specific cases, effective interventions were found at the cancer-notification, the progressive-therapeutic, and the progressive-relapsestages. Conclusion: This study suggested that interventions for breast cancer patients by a clinical psychologist are effective. The psychological interventions had two roles: to assess the patients properly and to interview the patients as purposefully as a medical team member would.