A flexible fiber in-forced hose comprises an inner rubber layer, an outer rubber layer, and a fiber reinforced layer provided between the inner rubber layer and the outer rubber layer, wherein the fiber reinforced layer is constructed by using a reinforcing fiber of at least one raw yarn, which is a spanized yarn consisting of mono-filaments made of a para aromatic poly-amide material. Such a fiber reinforced hose has excellent heat resistance, tensile strength, and adhesiveness with the rubber layers, as well as durability against repetitive pressurization.