  Primordial stars formed in the early universe are thought to be hosted by
compact dark matter (DM) halos. If DM consists of Weakly Interacting Massive
Particles (WIMPs), such stars may be powered by DM annihilation during the
early phases of their evolutions. We study the pre-main sequence evolutions of
the primordial star using a detailed stellar evolution code under the
assumption that the annihilation of adiabatically contracted WIMPs DM within
the star provides a sufficient energy to sustain the stellar equilibrium. We
follow the evolution of accreting stars using several gas mass accretion rates
derived from cosmological simulations. We show that the stellar mass becomes
very large, up to 900 - 1000 M_sun when the star reaches the main-sequence
phase for a reasonable set of model parameters such as DM particle mass and the
annihilation cross section. During the dark star phase, the star expands over a
thousand solar-radii, while the surface temperature remains below 10^4 K. The
energy generated by nuclear reactions is not dominant during this phase. We
also study models with different gas mass accretion rates and the DM particle
masses. All our models for different DM particle masses pass the dark star
phase. The final mass of the dark stars is essentially unchanged for DM mass of
m_DM <= 10 GeV. Gravitational collapse of the massive dark stars will leave
massive black holes with mass as large as 1000 M_sun in the early universe.
