This is a many-body interatomic potential for H in body-centered cubic (bcc) Fe. The potential is developed based on extensive energetics and atomic configurations of an H atom and H-H interactions in Fe from density functional theory calculations. In detail, the potential is parameterized by fitting not only to a single H atom in the perfect bcc Fe lattice and to the properties of H trap binding to a vacancy and surfaces as being done by previous studies, but also to multiple H trapping to a vacancy and H-H interaction in Fe lattice.