word count: 299 words Abstract Movement related beta band cortical oscillations, including post-movement beta rebound and desynchronization/synchronization observed during Go/NoGo tasks, have drawn attention in motor control literature, particularly during movements of upper extremities. However, fewer study focused on beta band oscillations during postural control in upright stance. Here, we examined beta rebound and other components of electroencephalogram (EEG) activity during perturbed upright stance to investigate supraspinal contributions to postural stabilization. Particularly, we aimed to clarify the timing and duration of the beta rebound and other components within a non-sustained, but long-lasting, postural recovery process following perturbed stance that occurs much more slowly compared to upper extremities due to a larger time scale of mechanical dynamics. To this end, EEG signals were acquired from nine healthy young adults in response to an impulsive support-surface perturbation, together with the center of pressure (CoP), center of mass (CoM) and electromyogram (EMG) activities of ankle muscles. Event-related potentials (ERPs) and event-related spectral perturbations (ERSPs) were computed using the perturbation onset as a triggering event. Our results indicate that, after shortlatency (<0.3 s) ERPs, powers in high-beta and alpha bands decreased (event-related desynchronizations: ERDs) in the 0.3-0.6 s and 0.3-1.5 s time-intervals after the perturbation onset, respectively. This was followed by long-lasting theta band decrease (ERD) and high-beta increase (event-related synchronization: ERS), implying beta rebound. Specifically, the beta rebound sustained for approximately three seconds from 1.0 to 4.0 s. EMGs of the ankle muscles and joint torques of the ankle and hip were almost completely relaxed in the first half period of the beta rebound. In the remaining period, the CoP and CoM were in their final approach to the equilibrium with amplitudes comparable to those during quiet stance. Possible mechanisms of beta rebound and long-lasting theta-ERD may be related to underlying intermittent control strategy for upright stance.where we assumed that the foot-link is fixed on the moving support surface with no translational and rotational movement (̈F = , ̈F = 0, ̈f = 0). Moreover, we assumed that ( F − ANK ) = 0.02 m,