  An explicit model of $F(R)$ gravity with realizing a crossing of the phantom
divide is reconstructed. In particular, it is shown that the Big Rip
singularity may appear in the reconstructed model of $F(R)$ gravity. Such a Big
Rip singularity could be avoided by adding $R^2$ term or non-singular viable
$F(R)$ theory to the model because phantom behavior becomes transient.
