Dynamic behavior of a structure changes due to presence of crack. Scientific analysis of such phenomena can be utilized for fault diagnosis and detection of cracks in structures. In this paper, attempts have been made to detect the cracks of a mild steel rotating shaft. Theoretical expressions have been developed for determining natural frequencies and mode shapes for rotating shaft using flexibility influence coefficients and local stiffness matrix. The numerical results for the beams having'no'crack,'single'crack and'two'cracks are compared. It is observed from the numerical results that, there are appreciable changes in vibration characteristics of the rotating shaft with and without cracks which can be utilized for multi crack identification of structures.