A printer is provided that includes a printing unit printing an image on a sheet being conveyed on a printing path, a first feeder unit configured such that a sheet placed thereon is fed to the printing path via a first feeding path, a second feeder unit configured such that a sheet placed thereon is fed to the printing path via a second feeding path even while the first feeder unit is being replenished with sheets, and a controller configured to, in response to a first requirement being satisfied while the first feeder unit is forbidden to be replenished with sheets during a continuous printing operation, switch an actually-working feeder unit that works for actual sheet feeding in the continuous printing operation, to the second feeder unit, the first requirement including a condition that one or more sheets are placed on the second feeder unit.