  In order to treat tensor force explicitly, we propose a microscopic model for
nuclear structure based on antisymmetrized molecular dynamics (AMD). As a
result of the present study, it is found that some extentions of the AMD method
are effective to incorporate the tensor correlation into wave functions.
Calculating the deuteron, triton and $^4$He with the extended version of AMD,
we obtained solutions that have large contribution of the tensor force. By
analyzing the wave funtion of $^4$He, it is found that its single-particle
orbits are composed of normal-size $0s$ orbits and shrunk $p$ orbits so as to
gain the tensor force.
