Single crystal neutron diffractometer is a powerful tool to obtain the structure and magnetic information of various materials including the light elements. Two single crystal time-of-flight neutron diffractometers have been newly constructed at the Materials and Life Science Experimental Facility (MLF), J-PARC. One is IBARAKI biological crystal diffractometer called iBIX dedicated for structural biology and chemistry. The other is extreme environment single crystal diffractometer called SENJU for solid state physics and chemistry field. A brief introduction, specification of these diffractometers and examples of experimental results by using them are reported in this paper.