To provide a novel flexible acrylic copolymer replaced with a flexible vinyl chloride resin which does not contain a halogen atom, a production method thereof and a flexible resin composition containing the copolymer.

The flexible acrylic copolymer comprises a copolymer of a methyl methacrylate of 40-70 wt.% and a n-butyl acrylate of 60-30 wt.% and it has the reduced viscosity of 0.9-3.0 dl/g, a glass transition point of 90°C or less and tanδ at 20°C of 0.07 or more. The copolymer is produced by suspension polymerization or the like. The flexible resin composition is obtained by adding a plasticizer to the copolymer.