A high-electron mobility transistor includes a substrate, a gate electrode, a drain electrode, a source electrode and a first field plate. The substrate includes an active region. The gate electrode is disposed on the substrate. The drain electrode is disposed at one side of the gate electrode. The source electrode is disposed at another side of the gate electrode. The first field plate is electrically connected with the source electrode and extends from the source electrode toward the drain electrode. An overlapping area of the first field plate and the gate electrode is smaller than an overlapping area of the gate electrode and the active region.