An image scanning apparatus includes a sheet loading unit, a pickup roller, a first conveying roller, a detecting unit, a first stepping motor, a second conveying roller, a second stepping motor, a scanning unit, and a control unit that starts driving of the second stepping motor after performing phase matching of the second stepping motor. The control unit starts driving of the first stepping motor without performing phase matching of the first stepping motor. When an instruction to start scanning is input, the control unit starts the phase matching of the second stepping motor. When the detecting unit detects the document, the control unit starts driving of the first stepping motor after completion of the phase matching of the second stepping motor. When the detecting unit detects no document, the control unit starts driving of the first stepping motor before completion of the phase matching of the second stepping motor.