817系は2001年から営業運転を行っています。815系を基に、転換クロスシートと黒を基調とする配色を採用しました。筑豊本線と篠栗線を合わせた愛称「福北ゆたか線」のほか、長崎地区でも見られます。
Series 817 has been in service since 2001. Based on Series 815, it is equipped with reversible seats and a black-based color scheme. It can be seen on the Chikuho and Sasaguri lines, marketed together as the Fukuhoku Yutaka Line, as well as in the Nagasaki area.