This paper presents a performance evaluation of tandem queueing systems by machine learning. Recently, tandem queueing systems have been increasing in variety of service formats. Hence, it is important for service design to evaluate the performance of tandem queueing systems. However, the exact solutions of tandem queueing systems have not been fully developed. Alternatively, we can apply the discrete simulation to evaluate the performance. However, it takes much time. In this paper, we propose the performance evaluation method by machine learning to solve the problems.