The J-PARC RCS accelerates 2 bunches at the harmonic number 2. The major Fourier component of the beam current is even harmonics. However, the odd harmonics grow under some conditions even though they are very small amplitude at the beginning. We describe the the particle tracking simulation results for the odd harmonic beam loading effect in the RCS. Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea
