BACKGROUND The suitability of Frankl's logotherapy for the spiritual care (psychotherapy) of cancer patients in Japan is suggested. Using Functional Assessment of Chronic Illness Therapy-Spiritual (FACIT-Sp, Japanese version), the Purpose in Life test (PIL test, Japanese version), and WHO-Subjective Inventory (WHO-SUBI, Japanese version), we attempted to elucidate the complicated structure of spirituality in cancer patients in order to identify possible approaches to their spiritual care and means of evaluating such care. METHODS Two hundred and ninety-eight cancer patients participated in the study. All three tests were taken at the same time, and the results were evaluated by principal component analysis. RESULTS It was demonstrated that all the subscales employed in the present study could be represented by a two-dimensional structure (two principal components), and that the FACIT-Sp and PIL tests have similar contents. CONCLUSIONS FACIT-Sp (Japanese version) is very similar in conception to the PIL test, which was prepared in accordance with logotherapy. The results suggest that this test can serve as an adequate evaluation scale for measuring the effectiveness of spiritual care based on Frankl's logotherapy.