Surface electromyography (sEMG) signals contain information about a users intention. With this in mind, several types of sEMG electrodes have been proposed to reliably measure sEMG signals. Microneedle array (MNA) electrodes have been proposed to measure low skin impedance sEMG signals without any additional medium. However, the MNA electrode is vulnerable to motion owing to its small skin contact area. Therefore, the sEMG signal measured by the MNA electrode significantly depends on the skin contact condition. This paper proposes pneumatic sleeve-assisted microneedle-based sEMG signal measurement. The pneumatic sleeve provides stable skin contact during dynamic motions by using compressed air to secure the electrodes. The performance of the pneumatic sleeve-assisted sEMG signal measurement was compared with that of Velcro band-based sEMG signal measurement to demonstrate the usefulness of the pneumatic sleeve for sEMG signal measurement.