Metal additive manufacturing has many possibilities in various fields. However, a metallic structure produced by an additive manufacturing technique may have anisotropy that is caused during the manufacturing processes. Fatigue is well known cause of failure of engineering structure. If we applied the additive manufacturing technique to produce aerospace and automotive structures/parts, we must consider their fatigue lives. In this research, fatigue crack propagation experiments using a beach mark method were carried out on specimens that were produced by the additive manufacturing technique (Figure 1). After these tests, a crack propagation law was identified from beach marks on the fracture surfaces. However, the identified crack propagation law was found to have an anisotropy. Then, crack propagation analyses were performed based on the software system that was developed by Okada and his colleagues [1,2]. In the software system, only the quadratic tetrahedral element is used, enabling the use of an automatic mesh generation program. In present study, the stress intensity factor was computed by a J-integral method (see for the J-integral [3]). Since only the tetrahedral elements are used in present study, a domain integral method which is specialized for the tetrahedral element that was proposed by Okada and Ohata [4] was adopted. The results of the experiment and the numerical analyses (Figure 2) are presented at the conference.