An epoxy-resin composition of the components (A), (B), (D) and (E), where component (A) is an epoxy resin having an oxazolidone-ring structure, (B) is a bisphenol bifunctional epoxy resin with a number-average molecular weight of at least 600 but no more than 1300, which does not have an oxazolidone-ring structure, (D) is a triblock copolymer, and (E) is a curing agent. A film made of the epoxy-resin composition, a prepreg and a fiber-reinforced plastic is also disclosed. The epoxy resin composition is capable of achieving both a processability of a prepreg at room temperature and a suppression of voids in the molded product. A fiber-reinforced plastic having excellent mechanical properties, especially excellent fracture toughness and heat tolerance, is also obtained by using the epoxy-resin composition.