IgG4-related hypophysitis is a novel clinical disease entity, which is typically complicated by hypopituitarism. The objective of the study was to describe a novel case of IgG4-related hypophysitis without pituitary insufficiency and summarize the current relevant literature. A 55-year-old Japanese man presented with an enlarged pituitary gland and bitemporal hemianopsia. Endocrine studies revealed normal pituitary function, although his serum IgG4 level was high. The patient underwent a transsphenoidal biopsy of the pituitary gland, and the pathological tissues were consistent with IgG4-related hypophysitis. Oral prednisolone therapy was started, and after 6 months, his serum IgG4 level decreased and visual field improved. We described the first case of IgG4-related hypophysitis without pituitary insufficiency. However, further case collection is needed to characterize the pathophysiology of IgG4-related hypophysitis.