The present invention addresses the problem of providing a medicinal agent for suppressing the progression and recurrence of cancer and/or for treating cancer, the medicinal agent comprising a novel active ingredient having the effect of enhancing immunity to cancer. This Allergin-1 antagonist has the effect of enhancing immunity to cancer, and can be used for suppressing the progression and recurrence of cancer and/or for treating cancer. In particular, this Allergin-1 antagonist is useful for treating cancer patients for whom the therapeutic effects of anti-tumor immunotherapeutic agent are insufficient, or useful for cancer treatments in combination with anti-cancer drugs.
