  In neutron star crust, non-uniform structure of nuclear matter is expected,
which is called the "pasta" structure. From the recent studies of giant flares
in magnetars, these structures might be related to some observables and
physical quantities of the neutron star crust. To investigate the above
quantities, we numerically explore the pasta structures with a fully
threedimensional geometry and study the properties of low-density nuclear
matter, based on the relativistic mean-field model and the Thomas-Fermi
approximation. We observe typical pasta structures for fixed proton
number-fraction and two of them for cold catalyzed matter. We also discuss the
crystalline configuration of "pasta".
