A masterbatch comprising: aluminum particles; a heat-resistant wetting agent; a resin; and optionally a wax, wherein the proportion of the aluminum particles in the masterbatch is 50 to 80% by weight, the resin has a melt flow rate of 0.2 to 60 g/10 min, and the proportion of wax having a melt flow rate of more than 60 g/10 min and a melt viscosity at 140°C of 15 to 8000 mPa·s in the masterbatch is 10% by weight or less, wherein in the case of the heat-resistant wetting agent having a boiling point, the heat-resistant wetting agent is one having a boiling point of 250 °C or higher, in the case of the heat-resistant wetting agent that are volatilized into a gas by pyrolysis before boiling, the heat-resistant wetting agent is one having an intermediate pyrolysis temperature of 250 °C or higher in a nitrogen atmosphere, wherein the intermediate pyrolysis temperature is determined according to JIS K 7120 using a thermogravimetric balance, wherein the resin is selected from the group consisting of polyolefin resin, polyacetal resin, polystyrene resin, acrylonitrile resin, ABS resin, PMMA resin, polycarbonate resin, PBT resing, and/or PET resin, the wax is selected from the group consisting of polyethylene wax, polypropylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax and carnauba wax, and/or products obtained by modifying these waxes with acid, and the heat-resistant wetting agent is selected from the group consisting of polyethylene glycols, triphenyl phosphate, bis(2-ethylhexyl)phthalate, dibutyl phthalate, bis(2-ethylhexyl)adipate, dibutyl adipate, bis(2-ethylhexyl)sebacate and dibutyl sebacate, wherein the melt flow rate is measured according to JIS K 7210: 1999 (ISO 1333: 1997) at a temperature of 190°C and a load of 2.16 kg and the melt viscosity is measured with a Brookfield viscometer at a temperature of 140°C. aluminum particles; a heat-resistant wetting agent; a resin; and optionally a wax, wherein the proportion of the aluminum particles in the masterbatch is 50 to 80% by weight, the resin has a melt flow rate of 0.2 to 60 g/10 min, and the proportion of wax having a melt flow rate of more than 60 g/10 min and a melt viscosity at 140°C of 15 to 8000 mPa·s in the masterbatch is 10% by weight or less, wherein in the case of the heat-resistant wetting agent having a boiling point, the heat-resistant wetting agent is one having a boiling point of 250 °C or higher, in the case of the heat-resistant wetting agent that are volatilized into a gas by pyrolysis before boiling, the heat-resistant wetting agent is one having an intermediate pyrolysis temperature of 250 °C or higher in a nitrogen atmosphere, wherein the intermediate pyrolysis temperature is determined according to JIS K 7120 using a thermogravimetric balance, wherein the resin is selected from the group consisting of polyolefin resin, polyacetal resin, polystyrene resin, acrylonitrile resin, ABS resin, PMMA resin, polycarbonate resin, PBT resing, and/or PET resin, the wax is selected from the group consisting of polyethylene wax, polypropylene wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax and carnauba wax, and/or products obtained by modifying these waxes with acid, and the heat-resistant wetting agent is selected from the group consisting of polyethylene glycols, triphenyl phosphate, bis(2-ethylhexyl)phthalate, dibutyl phthalate, bis(2-ethylhexyl)adipate, dibutyl adipate, bis(2-ethylhexyl)sebacate and dibutyl sebacate, wherein the melt flow rate is measured according to JIS K 7210: 1999 (ISO 1333: 1997) at a temperature of 190°C and a load of 2.16 kg and the melt viscosity is measured with a Brookfield viscometer at a temperature of 140°C.