Containing metal soap particles having 6 to 22 carbon atoms of fatty acid and an inorganic crystal nucleating agent having an average particle diameter of 0.01 to 20 μm incorporated in the metal soap particles, the volume standard of the metal soap particles A metal soap having a 50% cumulative diameter of 1.0 to 30.0 μm and an internal uptake rate A represented by the following formula (1) of 30% or more. Internal uptake ratio A = 100− (X / X ′) × 100 (1) Formula X； content X ′ of inorganic crystal nucleating agent in metal soap； in metal soap pulverized material that has passed through a 325 mesh filter Content of inorganic crystal nucleating agent (where X and X ′ are in the range of 15 μm square under conditions of acceleration voltage 10 kV and height 15 mm by scanning electron microscope / energy dispersive X-ray spectroscopy (SEM / EDX)) The average value obtained by elemental analysis at three locations.)脂肪酸の炭素数が６～２２の金属石鹸粒子と、前記金属石鹸粒子の内部に取り込まれた平均粒子径が０．０１～２０μｍの無機結晶核剤とを含有し、前記金属石鹸粒子の体積基準における５０％積算径が１．０～３０．０μｍであり、下記（１）式で表される内部取込率Ａが３０％以上である金属石鹸。 内部取込率Ａ＝１００－（Ｘ／Ｘ’）×１００・・・（１）式 Ｘ ；金属石鹸における無機結晶核剤の含有量 Ｘ’；３２５メッシュのフィルターを通過した金属石鹸粉砕物における無機結晶核剤の含有量（但し、Ｘ及びＸ’は、走査型電子顕微鏡／エネルギー分散型Ｘ線分光法（ＳＥＭ／ＥＤＸ）により、加速電圧１０ｋＶ、高さ１５ｍｍの条件下、１５μｍ四方の範囲で３箇所を元素分析して得られる平均値である。）
