A mobile communication system according to the present invention is a mobile communication system that supports a D2D (Device-to-Device) proximity service in which direct communication not passing through a network is enabled, and comprises: a first user terminal configured to transmit notification information for notifying presence of first D2D communication data scheduled to be directly transmitted to another user terminal. The first user terminal is further configured to transmit, after transmitting the notification information, control information indicating a location of a data resource used for transmitting the first D2D communication data.