  We consider 2+1 dimensional off-shell N = 1 pure supergravity that is
constructed from graviton, gravitino and auxiliary field. We show that the
$R^2$ supersymmetric invariant and $R^2_{\mu \nu}$ supersymmetric invariant are
expressed as local supersymmetric exact terms up to mass terms for gravitino.
In both cases, the mass parameter is proportional to the off-shell
supersymmetric cosmological constant.
