A printing device comprising: a printing unit that performs printing on a medium using liquid; a liquid container that includes a liquid containing chamber, which is capable of containing the liquid supplied to the printing unit, and a liquid inlet, which allows the liquid containing chamber to be filled with the liquid, wherein the liquid inlet projects above a top surface of the liquid container; a shell that accommodates the printing unit and a portion of the liquid container, wherein the liquid container includes a projecting portion that projects out of the shell; and a protection member that covers the projecting portion, wherein the protection member projects out of the shell in a direction that is the same as a direction in which the liquid container projects out of the shell; and a liquid supply unit that includes the liquid container, wherein a lower portion of the shell includes a medium setting portion on which the medium is set, the printing device is configured to transfer the set medium from a front part of the shell toward the printing unit and ejected to the front part of the shell, and a front surface of the liquid container is located frontward, which is a direction that is the same as a direction in which the liquid container projects out of the shell, from the medium setting portion, the liquid container is shaped to have a rectangular parallelepiped form as a whole; the liquid container is attached to the shell in a front surface attachment arrangement in which the liquid container projects out of a front surface of the shell and a longitudinal direction of the liquid container conforms to a rearward direction, which is a direction that is opposite to the direction in which the liquid container projects out of the shell, of the shell, the shell includes a holding portion that is capable of holding the liquid supply unit in a positioned state, and wherein the printing device includes an aligning mechanism (70, 73) that aligns the liquid container and the holding portion when the liquid container is attached to the holding portion, wherein the aligning mechanism (70, 73) includes: a guide included in one of the liquid supply unit and the holding portion, wherein the guide extends in a direction in which the liquid supply unit is coupled to the holding portion; and a sliding portion included in the other one of the liquid supply unit and the holding portion, wherein the sliding portion slides relative to the guide when the liquid supply unit is coupled to the holding portion. a printing unit that performs printing on a medium using liquid; a liquid container that includes a liquid containing chamber, which is capable of containing the liquid supplied to the printing unit, and a liquid inlet, which allows the liquid containing chamber to be filled with the liquid, wherein the liquid inlet projects above a top surface of the liquid container; a shell that accommodates the printing unit and a portion of the liquid container, wherein the liquid container includes a projecting portion that projects out of the shell; and a protection member that covers the projecting portion, wherein the protection member projects out of the shell in a direction that is the same as a direction in which the liquid container projects out of the shell; and a liquid supply unit that includes the liquid container, wherein a lower portion of the shell includes a medium setting portion on which the medium is set, the printing device is configured to transfer the set medium from a front part of the shell toward the printing unit and ejected to the front part of the shell, and a front surface of the liquid container is located frontward, which is a direction that is the same as a direction in which the liquid container projects out of the shell, from the medium setting portion, the liquid container is shaped to have a rectangular parallelepiped form as a whole; the liquid container is attached to the shell in a front surface attachment arrangement in which the liquid container projects out of a front surface of the shell and a longitudinal direction of the liquid container conforms to a rearward direction, which is a direction that is opposite to the direction in which the liquid container projects out of the shell, of the shell, the shell includes a holding portion that is capable of holding the liquid supply unit in a positioned state, and wherein the printing device includes an aligning mechanism (70, 73) that aligns the liquid container and the holding portion when the liquid container is attached to the holding portion, wherein the aligning mechanism (70, 73) includes: a guide included in one of the liquid supply unit and the holding portion, wherein the guide extends in a direction in which the liquid supply unit is coupled to the holding portion; and a sliding portion included in the other one of the liquid supply unit and the holding portion, wherein the sliding portion slides relative to the guide when the liquid supply unit is coupled to the holding portion. a guide included in one of the liquid supply unit and the holding portion, wherein the guide extends in a direction in which the liquid supply unit is coupled to the holding portion; and a sliding portion included in the other one of the liquid supply unit and the holding portion, wherein the sliding portion slides relative to the guide when the liquid supply unit is coupled to the holding portion.