An inkjet printing device comprises an inkjet print head, a carriage on which the print head is mounted and which moves to and fro in a main scan direction while facing a sheet, a detector unit mounted on the carriage and detecting whether or not the sheet exists at a position facing a detecting position (prescribed position of the carriage in the main scan direction), an acquisition unit which acquires a print command including size information specifying sheet size, a setting unit which sets the detecting position depending on the size information, a moving unit which moves the carriage to the detecting position set by the setting unit, and a checking unit which checks whether the sheet exists at the position facing the detecting position by use of the detector unit after the carriage is moved to the detecting position and before the printing on the sheet is started.