To provide a steel for machine structure superior in hydrogen fatigue fracture resistance having tensile strength of 1800 MPa or higher, and a manufacturing method therefor.

The steel for machine structure superior in hydrogen fatigue fracture resistance, is characterized by including, by mass%, 0.1-0.6% C, less than 0.5% Si, 0.1-0.5% Mn, 0.4-3.0% Mo, 0.02-0.5% V, 0.02% or less P, and 0.02% or less S, satisfying 5≤(Mo/V)≤20, and further including a predetermined amount of one or more sort among Cr, Ni, Cu, Al, Ti, Nb, B, or N, as needed, and the balance Fe with unavoidable impurities. The method for manufacturing the steel for machine structure superior in hydrogen fatigue fracture resistance is characterized by quenching the steel consisting of the above components, and then tempering it at 500°C or higher.