To characterize Parkinson disease, abnormal phase-amplitude coupling is assessed in the cortico-basal circuit using invasive recordings. Whether the same phenomenon might be found in areas other than the cortico-basal ganglia circuit is unknown. We hypothesized that using magnetoencephalography to assess phase-amplitude coupling in the whole brain can characterize Parkinson disease. We recorded resting-state magnetoencephalographic signals in patients with Parkinson disease and in healthy age- and sex-matched participants. We compared the whole-brain signals from the two groups, evaluating the power spectra of 3 frequency bands (alpha, 8–12 Hz; beta, 13–25 Hz; gamma, 50–100 Hz) and the coupling between the gamma amplitude and the alpha or beta phases. Compared with the healthy participants, the patients with Parkinson disease showed significant beta–gamma phase-amplitude coupling in the sensorimotor, occipital, and temporal cortices. In contrast, the two groups showed no significant difference in their resting-state powers. Further, in a resting state, the beta–gamma phase-amplitude coupling in the sensorimotor cortices correlated significantly with motor symptoms of Parkinson disease (P < 0.05); the beta-band power did not. We thus demonstrated that beta–gamma phase-amplitude coupling in the resting state characterizes Parkinson disease.