A liquid-He-free dilution refrigerator, 'mK cryocooler', for neutron scattering research was developed. The mK cryocooler is composed of a pulse tube cryocooler as 4 K stage and a Joule-Thomson type dilution refrigerator as mK stage. The lowest sample temperature obtained in neutron scattering experiments was 41 mK. An automatic cooling operation was developed. We expect that any researcher is able to carry out neutron scattering experiments at mK temperatures with good movability, easy handling, low running cost, stable and continuous operation, and no neutron beam loss.