  We perform a three dimensional radiation hydrodynamics simulation to
investigate the formation of first stars from initial collapse of a primordial
gas cloud to formation and growth of protostars. The simulation is integrated
until 0.1 Myrs after the formation of the primary protostar by which the
protostars have already settled onto main sequence stars. This is the first
attempt of simulating first star formation to take into account the ultraviolet
radiative feedback effect by the multiple protostars as well as the three
dimensional effects such as fragmentation of the accretion disk. We find that
the mass accretions onto the population III protostars are significantly
suppressed by the radiative feedback from themselves. As a result, we find five
stars formed in this particular simulation, and that the final mass of the
stars are < 60Msun, including a star of 4.4Msun. Formation of such a star hints
at the existence of even lower-mass stars that would live today.
