Provided are a method for manufacturing a magnesium fluoride sintered compact in which cracking or chipping is suppressed and relative density is increased, a method for manufacturing a neutron moderator, and a neutron moderator. The method for manufacturing a magnesium fluoride sintered compact includes a powder packing step (S1) for tap packing a magnesium fluoride powder material into a die, and an intermediate-body sintering (pulsed electric current sintering) step (S2) for performing pulsed electric current sintering for sintering the packed magnesium fluoride powder material while applying a pulsed electric current thereto, and obtaining a magnesium fluoride sintered compact (intermediate body).
