Log analysis is one of the most fundamental task of intrusion detection. In recent years, since a number of computers and network security devices increases, it is required to analyze multiple logs produced by them. However, log analysis is done with text-based techniques and it is inefficient for analyzing of multiple logs. We developed a visualization system for analysis of multiple logs which visualizes the frequency of events by timeline. We analysed logs produced by a honeypot by using the system, and showed its effectiveness.