The sound field in an irregular-shaped reverberation room was analyzed using finite element method (FEM) to evaluate the resulting accuracy of the FE-analysis of sound field with irregular-shaped elements. Next, absorption modeling techniques with the assumption of locally reactiveness and with absorbent finite element were examined by comparing the accuracies in the sound field analysis, and the latter modeling was found to give the better result when transmitting acoustic energy exists. Finally, the standard deviations of sound pressure distribution in the reverberation room was calculated using results of sound field analysis by the FEM.