A procedure for updating the Park-Ang damage index of reinforced concrete building under near-fault ground motion is proposed. Rather than developing a new damage model, a correction term is added to the existing damage model within the Bayesian framework. The correction term is described as a linear function of the variation of stiffness of structures which is a more consistent indicator in predicting the level of damage. The Bayesian method is an effective approach when new data become available. The reinforced concrete building damage data during past near-fault pulse-like earthquakes were used in updating the damage model. The proposed damage index is conceptually simple and realistic.