A masterbatch of a liquid additive is provided, the resin composition for the masterbatch comprising (a) a block copolymer or a hydrogenated product thereof, the block copolymer containing a polymer block having a vinyl aromatic compound as a main component and a polymer block having a conjugated diene compound as a main component, and 40 to 100 parts by mass of a polyolefinic resin and 100 to 150 parts by mass of an ethylene·α-olefin copolymer with respect to 100 parts by mass of the (a) component, wherein the kinematic viscosity at 100° C. is 10 to 5,000 mm2/s; the ethylene molar content is in the range of 30 to 85 mol %; and the molecular weight distribution (Mw/Mn) for the molecular weight measured by gel permeation chromatography (GPC) with reference to polystyrene is not more than 2.5.