A method for producing a magnesium fluoride sintered body, a method for producing a neutron moderator, and a neutron moderator in which relative density is increased by suppressing cracking or chipping are provided. The method for producing a magnesium fluoride sintered body includes a powder filling step S1 in which a magnesium fluoride powder material is tapped and filled in a mold, and a pulse for sintering the filled magnesium fluoride powder material while energizing a pulse. Intermediate sintering (pulse electric current sintering) step S2 for performing current sintering to obtain a magnesium fluoride sintered body (intermediate).割れ又は欠けを抑制して相対密度を高めたフッ化マグネシウム焼結体の製造方法、中性子モデレータの製造方法及び中性子モデレータを提供する。フッ化マグネシウム焼結体の製造方法は、フッ化マグネシウム粉末材を金型にタッピング充填を行う粉体充填工程Ｓ１と、充填されたフッ化マグネシウム粉末材を、パルスを通電しながら焼結するパルス通電焼結を行い、フッ化マグネシウム焼結体（中間体）を得る中間体焼結（パルス通電焼結）工程Ｓ２と、を含む。
