A resin composition capable of providing filaments superior in bleeding performance of an insect-controlling agent in the initial stage of use thereof is disclosed. The present invention relates to a resin composition for filaments, comprising a high-density polyethylene, an insect-controlling agent and synthetic silica, wherein the density of the high-density polyethylene is from 935 to 965 kg/m3, and the MFR thereof, from 0.1 to 6 g/10 mins； wherein the average pore radius of the synthetic silica is from 0.040 to 0.105 m； and wherein said resin composition contains 100 parts by weight of the high-density polyethylene, and 0.1 to 10 parts by weight of the insect-controlling agent and 0.1 to 10 parts by weight of the synthetic silica per 100 parts by weight of the high-density polyethylene.
