A printer, comprising: a printer housing, which includes a plurality of outer surfaces including a bottom surface opposed to an installation surface, and has a recording paper receiving portion configured to receive recording paper through an opening portion; a printer cover, which is coupled to the printer housing, and is configured to openably cover the opening portion; a printer display device, which is removably mounted to the outer surface, of the plurality of outer surfaces, other than the bottom surface, and is configured to display predetermined information; a connection cable, which is connected between the printer housing and the printer display device, and is configured to communicate at least data related to the predetermined information; and a delivery slot for the recording paper located on an opposite side of the printer housing to the printer display device; the printer display device including: a fixing portion separably mounted to the outer surface; a display portion main body having a display portion configured to display the predetermined information provided thereon; and a hinge portion configured to couple the fixing portion and the display portion main body to each other so that the display portion main body can be displaced relative to the fixing portion; wherein the hinge portion has a rotation axis extending in parallel to each of the installation surface and the outer surface to which the printer display device is mounted, wherein the display portion main body is coupled to the fixing portion so as to be rotated about the rotation axis through intermediation of the hinge portion, wherein the printer housing further includes, as the plurality of outer surfaces, a top surface opposed to the bottom surface, wherein the display portion main body is configured to be displaced by rotation about the rotation axis between a first position at which the display portion main body is overlapped with the fixing portion and a second position at which the display portion is positioned above the top surface; and wherein when the display portion main body is in the second position, the display portion is inverted vertically and is visually recognizable from the delivery slot side. a printer housing, which includes a plurality of outer surfaces including a bottom surface opposed to an installation surface, and has a recording paper receiving portion configured to receive recording paper through an opening portion; a printer cover, which is coupled to the printer housing, and is configured to openably cover the opening portion; a printer display device, which is removably mounted to the outer surface, of the plurality of outer surfaces, other than the bottom surface, and is configured to display predetermined information; a connection cable, which is connected between the printer housing and the printer display device, and is configured to communicate at least data related to the predetermined information; and a delivery slot for the recording paper located on an opposite side of the printer housing to the printer display device; the printer display device including: a fixing portion separably mounted to the outer surface; a display portion main body having a display portion configured to display the predetermined information provided thereon; and a hinge portion configured to couple the fixing portion and the display portion main body to each other so that the display portion main body can be displaced relative to the fixing portion; a fixing portion separably mounted to the outer surface; a display portion main body having a display portion configured to display the predetermined information provided thereon; and a hinge portion configured to couple the fixing portion and the display portion main body to each other so that the display portion main body can be displaced relative to the fixing portion; wherein the hinge portion has a rotation axis extending in parallel to each of the installation surface and the outer surface to which the printer display device is mounted, wherein the display portion main body is coupled to the fixing portion so as to be rotated about the rotation axis through intermediation of the hinge portion, wherein the printer housing further includes, as the plurality of outer surfaces, a top surface opposed to the bottom surface, wherein the display portion main body is configured to be displaced by rotation about the rotation axis between a first position at which the display portion main body is overlapped with the fixing portion and a second position at which the display portion is positioned above the top surface; and wherein when the display portion main body is in the second position, the display portion is inverted vertically and is visually recognizable from the delivery slot side.