Depression is common among cancer patients and their families, and may lead to substantial clinical consequences. Clinicians should routinely screen cancer patients for comorbid depression and should provide appropriate care at both primary and specialized care levels. Good quality care is beneficial not only for cancer patients themselves but also for their family members. It includes good communication between patients and health providers, and addressing of unmet needs of cancer patients. Specialized care comprises pharmacotherapy and psychotherapy. The advancement of psychotherapy for cancer patients parallels the advancement of general psychotherapy. Among the many types of psychotherapies, mindfulness-based interventions have been attracting growing attention. Some relevant studies that have been conducted in Keio University Hospital are described herein.