In this study, minimum shear reinforcement ratio of reinforced concrete structures was proposed as a function of concrete compressive strength, tensile strength of shear reinforcement, and tensile reinforcement ratio to prevent shear failures when inclined cracking occurs. Parametric studies were performed to investigate the effects of various design parameters on the minimum shear reinforcement. From the studies, it was found that the proposed method requires more minimum shear reinforcement than ACI 318-08 design code does when the longitudinal reinforcement ratio is less than 1.87 percent. In the comparison with existing test results, it was also find that the proposed method assures the nominal shear strength of concrete conservatively while ACI 318-08 does not.