There are provided a method for manufacturing a magnesium fluoride sintered compact to be free from cracks and chipping and to have high relative density, a method for manufacturing a neutron moderator, and the neutron moderator. The method for manufacturing a magnesium fluoride sintered compact includes a powder filling process S1 for filling a magnesium fluoride powder material into a die by tapping, and an intermediate body sintering (pulsed electric current sintering) process S2 for performing pulsed electric current sintering for sintering the filled magnesium fluoride powder material while applying a pulsed electric current thereto, to obtain a magnesium fluoride sintered compact (intermediate body).
