Document viewing apparatus and program

A document viewing apparatus, having a touch screen, capable of receiving a handwritten input operation by the user in a state where a document image is displayed on a touch screen, a character string detection unit for detecting a character string included in the document image, a reference position determination unit that sets the reference position when an object is assigned to the character string in accordance with the operating position or operation trace of the handwritten input operation, a guide line drawing unit for drawing and displaying a guide line in accordance with an operation trace with respect to the reference position, and an object assignment unit that assigns a guide line as an object to the character string with the completion of the handwritten input operation.