In this paper, the iterative decoding system using the nonbinary low-density parity-check (LDPC) code is studied in the magnetic recording system using a bit-patterned media (BPM) R/W channel affected by the write head field gradient, the media switching field distribution (SFD), the demagnetization field from adjacent dots, and the dot position deviation in an areal recording density of 2 Tb/in2. The performance of iterative decoding system using the nonbinary LDPC code over Galois field of GF(28) is evaluated by the computer simulation, and it is compared with the conventional iterative decoding system using the binary LDPC code. The results show that the nonbinary LDPC system provides better performance compared with the binary LDPC system.