The final mass of the first star is fixed when mass accretion to a protostar ceases. We report our recent 2-dimensional radiation-hydrodynamic simulations of the mass accretion process to the primordial protostar. The protostellar evolution is also simultaneously calculated by solving the stellar interior structure. Our preliminary calculation shows that a circumstellar disk forms around the primordial protostar. The disk is almost fully molecular, and surrounded by warmer neutral envelope. Mass accretion to the star takes place via this accretion disk at high rates exceeding several × 10-3 Mȯ yr-1. With such high accretion rates, total luminosity of the protostar approaches the Eddington luminosity before the protostar reaches the zero-age main sequence stage. Radiation pressure exerted on gas accretion envelope should regulate the mass accretion when the protostellar mass exceeds 80 Mȯ, which is before the stellar UV radiation influences the accretion flow.