A roller unit includes a roller, an arm, a holder, a tension spring, and a restriction member. The arm rotatably holds the roller. The holder swingably holds the arm. The tension spring includes a first hook at one end of the tension spring and a second hook at another end of the tension spring. The first hook is hooked on an arm-side hook of the arm. The second hook is hooked on a holder-side hook of the holder. The restriction member is configured to restrict movement of the tension spring in a state in which the first hook or the second hook is unhooked.