In this paper we develop the plane wave method for calculating photonic band structure in chiral medium through magnetic component, and on this basis, calculate the photonic band structure of the face centered cubic (fcc) lattice made of chiral medium. Result shows that the cut off frequency, below which no propagating modes exist, appears in the two kinds of fcc lattices, i.e.,the array of chiral “spherical atoms” in dielectric material and the array of dielectric “spherical atoms” in chiral matrix. The result is compared with that obtained through electric component, and the difference between them is discussed.