A liquid ejecting system comprising: a transport portion that transports a medium in a transport direction in a state in which the medium is supported on a medium supporting surface; a liquid ejecting portion that performs printing by moving in a scanning direction and ejecting a liquid from a nozzle with respect to the medium supported on the medium supporting surface; a designation portion for an operator to designate a designation range within a scanning area, the scanning area being configured to face the liquid ejecting portion that moves in the scanning direction and to include the medium and the medium supporting surface; and a control portion that sets a flushing area based on the designated designation range and performs a flushing operation of ejecting the liquid from the nozzle to the flushing area as a maintenance operation of the liquid ejecting portion, wherein the scanning direction is perpendicular to the transport direction, wherein the control portion displays, on a display portion included in the designation portion, a designatable range excluding a prohibited range configured not to be designated as the designation range, the prohibited range being a part of the scanning area that cannot be designated as the flushing area, characterized in that the transport portion has a transport belt that comprises the medium supporting surface and that transports the medium in the transport direction in a state in which the medium is supported on the medium supporting surface, an end of the transport belt in the scanning direction is included in the prohibited range, the medium supporting surface of the belt extends across a belt width, the medium extends across a medium width forming part of the belt width, and the printing area extends across a printing width forming part of the medium width in the scanning direction, and the designatable range includes both the medium and a portion of the medium supporting surface that does not support the medium, and excludes prohibited areas located at the ends of the printing area, the ends of the transport belt and the ends of the medium in the scanning direction. a transport portion that transports a medium in a transport direction in a state in which the medium is supported on a medium supporting surface; a liquid ejecting portion that performs printing by moving in a scanning direction and ejecting a liquid from a nozzle with respect to the medium supported on the medium supporting surface; a designation portion for an operator to designate a designation range within a scanning area, the scanning area being configured to face the liquid ejecting portion that moves in the scanning direction and to include the medium and the medium supporting surface; and a control portion that sets a flushing area based on the designated designation range and performs a flushing operation of ejecting the liquid from the nozzle to the flushing area as a maintenance operation of the liquid ejecting portion, wherein the scanning direction is perpendicular to the transport direction, wherein the control portion displays, on a display portion included in the designation portion, a designatable range excluding a prohibited range configured not to be designated as the designation range, the prohibited range being a part of the scanning area that cannot be designated as the flushing area, characterized in that the transport portion has a transport belt that comprises the medium supporting surface and that transports the medium in the transport direction in a state in which the medium is supported on the medium supporting surface, an end of the transport belt in the scanning direction is included in the prohibited range, the medium supporting surface of the belt extends across a belt width, the medium extends across a medium width forming part of the belt width, and the printing area extends across a printing width forming part of the medium width in the scanning direction, and the designatable range includes both the medium and a portion of the medium supporting surface that does not support the medium, and excludes prohibited areas located at the ends of the printing area, the ends of the transport belt and the ends of the medium in the scanning direction.