A network security apparatus includes a management unit, a security policies monitoring unit, a security monitoring unit, a log security check unit, and a log transmission unit. The management unit receives network security apparatus setting information, security policies and log generation policies from the outside. The security policies monitoring unit checks whether the security policies comply with a set format. If the security policies comply with the set format, the security monitoring unit monitors whether a communication node communicates in compliance with the security policies. The log security check unit generates a monitoring log based on the log generation policies, and checks whether the monitoring log complies with a log setting format. If the monitoring log complies with the log setting format, the log transmission unit transmits the security log to the outside, thereby performing the outside network security.