A therapeutic or prophylactic agent for radiation damage associated with radiation exposure, comprising an eosinophil-removing agent as an active ingredient and the like are provided as a technique for efficiently treating or preventing radiation damage associated with radiation exposure. According to the therapeutic or prophylactic agent comprising an eosinophil-removing agent according to the present invention, by suppressing migration and/or infiltration into target tissue and/or proliferation in the tissue of eosinophils and/or inhibiting the activity or function of the eosinophils, pathological conditions such as inflammatory responses and fibrosis of tissue can be suppressed to effectively treat or prevent radiation damage. Moreover, effective radiation therapy can be performed by suppressing radiation damage.