An object of the invention is to provide a communication system capable of broadcasting and distributing various types of messages. The communication system according to the present invention includes a network operator device (21) disposed in a network (20) managed by a carrier; and a distribution information determination device (30) disposed between the network operator device (21) and a plurality of application servers that provide an application service. The distribution information determination device (30) transmits, to the network operator device (21), a distribution message transmitted from any one of application servers according to an event notification transmitted from a communication device (10_1), and a distribution policy used to distribute the distribution message, and distributes the distribution message to a plurality of communication devices (10_1) to (10_3) based on the distribution policy.