The dynamic stress intensity factor is used to predict the brittle fracture of a structure subjected to a dynamic loading. The dynamic finite element method is a powerful tool for calculating the dynamic stress intensity factor. It, however, requires a large amount of computer time for a three-dimensional analysis. The line-spring model devised by Rice and Levy [1] is one of the approximate approaches to obtaining the stress intensity factors of cracks in three-dimensional structures. The finite element method combined with the line-spring model reduces a three-dimensional crack problem to a two-dimensional one, so that it reduces a large amount of computer time. Saka et al. [2] successfully applied the finite element method combined with a dynamic line-spring model to a frequency response analysis of the dynamic stress intensity factor of a crack in a three-dimensional structure subjected to a harmonic loading. Their method cannot be directly extended to a transient analysis. The present paper deals with a transient analysis of the dynamic stress intensity factor using the finite element method combined with a static line-spring model.