The present invention relates to a block copolymer (A) including a (meth)acrylic polymer block (a) and an acrylic polymer block (b). The (meth)acrylic polymer block (a) is preferably copolymerized with a monomer having a functional group having high cohesive force, such as a carboxyl group, so that the 5%-weight-loss temperature is 300.degree. C. or more or the tensile strength is 3 MPa or more, and the hardness measured by a type A durometer according to JIS K6253 is 50 or less, and a compression set measured after 22 hours at 70.degree. C. is 45% or less. The block copolymer (A) exhibits excellent thermal decomposition resistance and low compression set at high temperatures. The block copolymer (A) can be used as a soft material for automobile, and has low hardness, high adhesion, high oil resistance, high weather resistance, high heat resistance, high recycling property, high tensile properties, and high wax remover resistance.