In this paper, low-density parity-check (LDPC) coding and iterative decoding system is studied in the magnetic recording system using a bit-patterned medium (BPM). The magnetic recording system using BPM has a serious problem of requiring precise write synchronization to correctly write the recording sequence on each intended island. In this paper, an error locator using the parity-check matrix of LDPC code is utilized to curb the influence of write error on the iterative decoding process. The performance of the proposed system with the error locator is evaluated by computer simulation for magnetic recording system using BPM with synchronization write error at a recording density of 2 Tb/in2, and it is compared with a conventional Reed-Solomon (RS) encoding and decoding system. The results show that the proposed system provides better performance.