The invention provides a mobile communication system, a network node, and a mobile communication method, which can cause user equipment of a particular type to attach to a dedicated network regardless of whether or not the user equipment supports a low access priority indicator (LAPI). An MME (60) acquires subscriber information on UE (10) from an HSS (70) based on an attachment request from the UE (10) forwarded by an eNB (50), the subscriber information including availability for the UE (10) to use the dedicated network, and sends the eNB (50) a selection instruction to select the dedicated network based on the acquired subscriber information. When the eNB (50) receives the selection instruction from the MME (60), the eNB (50) determines a dedicated MME (60D) constituting the dedicated network, and transmits the attachment request from the UE (10) to the determined dedicated MME (60D).