  The low-lying level structures of $^{26}{\rm Ne}$, $^{28}{\rm Ne}$ and
$^{30}{\rm Ne}$ which are related to the breaking of the N=20 shell closure
have been studied by the framework of the deformed-basis antisymmetrized
molecular dynamics plus generator coordinate method using Gogny D1S force. The
properties of the many-particle and many-hole states are discussed as well as
that of the ground band. We predict that the negative-parity states in which
neutrons are promoted into $pf$-orbit from $sd$ orbit have the small excitation
energy in the cases of $^{28}{\rm Ne}$ and $^{30}{\rm Ne}$ which, we regard, is
a typical phenomena accompanying the breaking of N=20 shell closure. It is also
found that the neutron $4p4h$ structure of $^{30}{\rm Ne}$ appears in low
excitation energy which contains $\alpha + ^{16}{\rm O}$ correlations.
