Tinea cruris is a disease caused by fungal infection, which is highly contagious and recurrent. The sources of fungi are also diverse, such as frequently bathing or swimming in public baths. Some patients have athlete's foot, and if they wash their socks together with their underwear, it can lead to cross-infection. Additionally, those who often keep small animals, live or work in humid and hot environments, or bathe infrequently, are also at risk of contracting this disease. Once it occurs, applying conventional antifungal creams can typically cure it. During treatment, one should avoid public baths, soaking pools, and swimming. Bath towels and scrubbing cloths should be used separately from other family members, and socks and underwear should be washed separately and disinfected by sun exposure.