A field-effect transistor includes a source electrode, a drain electrode, a semiconductor structure including a channel provided between the source electrode and the drain electrode in a first direction. Gate main portions have a first gate main portion length in the first direction and a second gate main portion length in a second direction. Connection portions are alternatively connected to the gate main portions respectively in the second direction. Each of the connection portions has a first connection portion length in the first direction and a second connection portion length in the second direction. The first connection portion length is longer than the first gate main portion length. The second connection portion length is shorter than the second gate main portion length. An external connection section is to apply electric power to the gate electrode. A bypass electrode connects the external connection section to each of the connection portions.