It is an object of the present invention to provide round fiber-reinforced plastic strand, a manufacturing method thereof, and a fiber-reinforced sheet which eliminate limitation in forming speed and limit on number of products capable of being manufactured at a time, do not require use of a release agent, eliminate the necessity of operations such as roughing after forming, and thus permit a considerable reduction of the manufacturing cost and a remarkable increase in the product quality. The manufacturing method of the round fiber-reinforced plastic strand of the present invention comprises (a) a step of continuously feeding reinforcing fiber bundles f1 each comprising a plurality of reinforcing fibers arranged in a direction while twisting the reinforcing fiber bundles f1; (b) a step of impregnating the reinforcing fiber bundles f1 fed continuously with a matrix resin R; and (c) a step of heating the resin-impregnated reinforcing fiber bundles f2 while tensioning to a prescribed intensity, thereby forming the reinforcing fiber bundle into a circular cross-section and hardening the resin, and manufactures a fiber-reinforced plastic strand 2 having a circular cross-section.