With the chiral quark model, we have calculated the axial charges of the pentaquark states with (I, I 3 ) = ( 1 2 , 1 2 ) and J P = 1 2 ± , 3 2 ± , and 5 2 ± . The P c states with the same J P quantum numbers but different color-spinflavor configurations have very different axial charges, which encode important information on their underlying structures. For some of the J P = 3 2 ± or 5 2 ± pentaquark states, their axial charges are much smaller than that of the proton.PACS numbers: 14.20.Lq, 12.39.Fe 2 ± , 3 2 ± , 5 2 ± , and 7 2 + in the molecular model, the diquark-triquark model, and the diquark-diquark-antiquark model, respectively. In fact, different color-flavor structures lead to very different magnetic moments of the hidden-charm pentaquarks. In other words, the magnetic moments may be a useful tool to distinguish various models. The axial charge of the baryon state is also a fundamental observable. The axial charge of the nucleon was measured in the beta decay of the polarized neutrons [48,49]. The axial charge of the P c states can also be measured from their semileptonic decays in the future. Moreover, since the width of the P c (4380) state is quite large, its axial charge may be directly extracted from the process P c → P c + π → J/ψ + p + π once the P c (4380) state is produced.The mass and magnetic moment of the hidden-charm pentaquark state depend on both the light and the heavy quarks. In contrast, the axial charge of the P c state is very sensitive to the color, spin, and isospin configurations of the light quarks inside the pentaquarks. Consequently, the axial charges provide a new independent probe of the inner structures of the P c states.The chiral symmetry and its spontaneous breaking play a pivotal role in the low-energy regime, which inspired various versions of the chiral quark model [50][51][52][53][54]. The long-range one-pion-exchange force is introduced to model the interaction between the light quarks, together with the confinement and the one-gluon-exchange potential [55][56][57][58][59]. The chiral quark models are widely * Electronic address: wgj@pku.edu.cn † Electronic address: zhan-wei.liu@adelaide.edu.au ‡ Electronic address: zhusl@pku.edu.cn