The present invention provides a composition for forming a positive electrode of a secondary battery which includes a positive electrode active material, a conductive material, and a dispersing agent, in which the conductive material includes a carbon-based material having a specific surface area of 130 m2/g or more and an oil absorption number of 220 ml/100 g or more at 0.1 wt % to 2 wt % with respect to the total weight of the composition for forming a positive electrode, and the dispersing agent is introduced into the conductive material to form a conductive material-dispersing agent composite, and the conductive material-dispersing agent composite has a particle size distribution D50 of 0.8 μm to 1.2 μm, a positive electrode for a secondary battery and a secondary battery, which are manufactured using the same.