Master batch composition, polyolefin resin composition comprising the same, and molded product thereof

A master batch composition comprising 35 to 85% by mass of an additive for plastics, 5 to 25% by mass of an olefin polymer which satisfies conditions (i) to (iii) shown below, and 10 to 60% by mass of a polyolefin resin as a carrier,

• (i) the polymer has a mesopentad fraction [mmmm] of 20 to 80 mol %,
• (ii) the polymer has a melting point (Tm-D) of 0 to 100° C., defined as a peak top of a peak observed at the highest temperature side in a fusion endothermic curve obtained using a differential scanning calorimeter (DSC) by holding a sample at −10° C. for 5 minutes under a nitrogen atmosphere and then elevating the temperature at a rate of 10° C./minute, and
• (iii) the polymer has a weight average molecular weight (Mw), measured by a gel permeation chromatography (GPC) method, of 10,000 to 1,000,000 and a Mw/Mn ratio of Mw to Mn of 4 or less, wherein Mn is a number average molecular weight thereof measured by the GPC method.