Disclosed is a printer capable of being connected with a plurality of personal computers and having a plurality of paper ejection trays. The printer further comprises a plurality of display units respectively corresponding to the paper ejection trays. In a case where a two or more paper ejection trays are occupied by sheets which are ejected in response to at least one ejection instruction from same personal computer, the controller of the printer controls the display units to notify a user that the sheets are ejected to a plurality of paper.