A writing-plotting apparatus comprising a keyboard including a mode selector for selecting a writing or plotting mode, a carriage carrying a pen movably toward and away from a sheet of paper, a first memory for storing character pattern data representative of characters, a second memory for storing graphic pattern data representative of patterns of graphs, and a control device which, in the writing mode, reads out from the first memory the character pattern data corresponding to the operated character keys, and in the plotting mode reads out from the second memory the graphic pattern data. The control device is responsive to the read-out character or graphic pattern data and controls the operations of drives for feeding the paper along one axis, reciprocating the carriage along another axis perpendicular to the one axis, and moving the pen for contact and release with respect to the paper. The apparatus may comprise a converter which receives drive signals corresponding to the read-out data and converts the signals based on a desired size of the characters or graphs selected by a size selector, so that the converted drive signals are applied to the paper, carriage and pen drives.