A steel composite beam is manufactured by T-shaped steel, inverse T-shaped steels installed at opposite ends of the T-shaped steel, and vertical stiffeners installed on the inverse T-shaped steels. A method for manufacturing a composite beam using T-shaped steel and a method of constructing a structure using the same are capable of using less steel and minimizing dead weight of the composite beam compared to a steel composite beam having the same cross section and depth, and designing a cross section of the composite beam in an efficient and economical manner due to the pre-stress caused by tendons, providing easy connection with column members on the basis of length, providing efficient construction, easy management, and convenient construction for ceilings and finishing equipment due to light dead weight.