A user apparatus connectable to a block chain system is provided. The user apparatus includes a memory, a communication interface, and at least one processor configured to divide a block chain consisting of a plurality of blocks into an active area and an inactive area based on a predefined standard, store blocks included in the active area in a first portion of the memory, based on a transaction occurring in the block chain system, record information of the transaction in the blocks stored in the first portion of the memory, and control the communication interface to transmit transaction information satisfying a predefined condition among the transaction information stored in the first portion to a manager apparatus included in the block chain system.