Smooth communication between doctors and patients during medical interviews is regarded as a very significant part of successful medical practice. To improve the quality of medical interviews, it is important that doctors correctly grasp the pain symptoms and medical conditions of their patients. However, it is often difficult for doctors to measure the quality of pain symptoms based solely on the verbal expressions patients use because pain is a highly subjective experience. In medical interviews, Japanese patients frequently use onomatopoeia such as “kiri-kiri” or “gaN-gaN” to express their pain symptoms and medical conditions. Doctors try to grasp patients' conditions by using metaphors corresponding to the onomatopoeia being expressed. In our study, therefore, we focused on the relationship between onomatopoeia and metaphors, and developed a system which automatically proposes metaphors corresponding to the onomatopoeia inputted by users. Our system is expected to add support to medical practice interviews.