  We propose a cosmological model in the framework of Poincar\'e gauge gravity,
in which cosmological constant, inflaton, and dark matter candidate all
naturally originate. Cosmological constant originates in the process of
breaking of the Poincar\'e symmetries down to the Lorentz symmetries. We select
a gauge Lagrangian without any additional matter fields, which can be regarded
as a minimum extension of general relativity with two more massive modes from
the Lorentz connection. Numerical analysis shows that the scalar dominates a
slow-rolling inflation and the pseudo-scalar behaves as a dark matter
candidate.
