Document sheet conveying device, image processing apparatus, and document sheet conveying method

A document sheet conveying method of causing one or more processors to execute a first step, a second step, and a third step, the one or more processors being configured to control a document sheet conveying device including a conveying mechanism configured to sequentially convey document sheets placed on a document sheet placing portion to a document sheet discharge portion through an image reading position at which an image is read from each of the document sheets and a raising and lowering mechanism configured to raise and lower the document sheet placing portion, the document sheet discharge portion being provided below the document sheet placing portion, wherein

• whether or not any of the document sheets is placed on the document sheet placing portion is determined in the first step,
• whether or not any of the document sheets is placed on the document sheet discharge portion is determined in the second step, and
• raising and lowering operations by the raising and lowering mechanism are controlled in the third step on a basis of results of determinations made in the first step and the second step.