[en] The development of two-dimensional position sensitive neutron detectors that have performances of a fast response, an ultra small space-resolution and a high neutron efficiency are required for various neutron scattering experiments using very high intense pulse neutron sources. We have made a study for development of the micro-strip gas counter (MSGC) filled with helium-3 gas as a neutron sensitive material. The MSGC filled with high pressure of helium-3 gas requires a thick neutron-window that decreases the neutron detection efficiency. The MSGC with a large gap between the electrodes provides high neutron detection efficiency. However, the large gap decreases the neutron energy resolution and the response. For development of a MSGC having high neutron detection efficiency, we have studied pressure vessel structures, window materials, electrode gaps and the pressure of helium-3 mixture gas. As a result of the studies, it was clear that the MSGC with a dish-shaped chamber ca have neutron detection efficiency of more than 93% in a neutron energy range from 0.1 to 25meV of neutron energy. (author)