Metal Additive Manufacturing (Metal AM) is a net-shape manufacturing process which enables productions of complex geometries without machining. During the manufacturing process, the material experiences a localized and steep temperature gradient due to localized and intensive heat input. As the result, residual stresses and deformations remain after the manufacturing process is completed [1]. The purpose of the present study is to develop a computational methodology that can predict the deformations of Metal AM manufactured products. It is executed by large-scale parallel finite element analyses consisting of thermal and thermal elastic plastic analyses [2]. In order to simulate the Metal AM process, the method of Inactive Element [3] was adopted. In order to validate the analytical method, Metal AM samples with various cross-sectional shapes were produced. The Numerically predicted deformations are compared with the experimentally measured values. In addition, trial was made to shorten the computational time by simplifying a heat source model to reduce the number of time steps [4]. The simplified heat source model gives heat input to entire layer one by one, until all layers are stacked. Although trends of deformation distributions between the experiment and analysis did not quantitatively match, their orders agreed.