The present invention relates to a primer resin for semiconductor devices which comprises a polyamide resin represented by the following formula (1): (wherein, R1 represents a tetravalent aromatic tetracarboxylic acid residue selected from the group consisting of pyromellitic acid, 3,4,3′,4′-diphenyl ether tetracarboxylic acid, 2,3,6,7-naphthalenetetracarboxylic acid and 3,4,3′,4′-benzophenone tetracarboxylic acid, R2 represents at least one kind of divalent diamine residue selected from the group consisting of diamino-4,4′-hydroxydiphenylsulfone, 4,4′-diamino-3,3′5,5′-tetraethyldiphenylmethane and 1,3-bis-(aminophenoxy)benzene, and n is a repeating number and represents a positive number of 10 to 1000) and has a lead frame comprising copper or 42 alloy, a semiconductor device having said primer resin layer between a lead frame comprising copper or 42 alloy and a cured product of a sealing resin, and a semiconductor sealing epoxy resin composition containing said primer resin; and said semiconductor device has an extremely improved adhesiveness between said lead frame and a cured product of a sealing resin composition and also is excellent in heat resistance and low moisture absorption.