Immediate-type hypersensitivity responses to systemic corticosteroids are rare despite their widespread use. It is still controversial whether the responses rarely occur or are underdiagnosed in clinical settings. Many cases probably remain underdiagnosed because the symptoms often mimic symptoms of underlying diseases. This case report describes a 73-year-old man who had immediate hypersensitivity reactions after intravenous administration of hydrocortisone, which was primarily intended to prevent hypersensitivity reactions to contrast media. Whole body rash with pruritus developed shortly after the steroid injection. Since the patient already experienced rash and itching sense after contrast media and antihistamine injection, we conducted skin testing to figure out which drug triggered the hypersensitivity reactions. Intradermal skin tests revealed a positive response to hydrocortisone sodium succinate, which suggested his hypersensitivity reactions were developed by hydrocortisone. Being a common therapy for allergic reaction, corticosteroids themselves are rarely suspected of causing hypersensitivity reactions. Considering there is no typical symptom or standard diagnostic test, awareness of corticosteroid hypersensitivity reactions is of importance to make the diagnosis.