The present invention relates to an apparatus and method for report a Radio Link Failure (RLF) and discloses the operations of UE or an eNB and the operating schemes of a network according to a cause of RLF. More specifically, the operating efficiency of a network is improved by reporting the reception power or interference power or both of other transceivers within a device, from among causes that generate RLF. This specification includes elements for configuring detecting RLF, configuring an RLF report on the RLF, and transmitting the RLF report. The RLF report includes information about whether there was an influence of In-device COexistence interference (ICO) to the RLF.