A polyarylene sulfide resin composition with an improved moldability and heat resistance is provided which comprises (a) 40 to 99% by weight of a polyarylene sulfide resin and (b) 1 to 60% by weight of a polyparabanic acid having the following recurring unit: ##STR1## wherein Z and Z.sup.1 are oxygen atoms or NH group, Z and Z.sup.1 being not simultaneously NH groups, and R is ##STR2## wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are hydrogen atoms or methyl groups, and X and X.sup.1 are bonds, CH.sub.2 groups, oxygen atoms, sulfur atoms, SO.sub.2 groups, CO groups or ##STR3##