This screen printing device is provided with: a single camera in which an imaging unit for capturing images of substrates and screen masks is disposed in such manner that the incident light axis thereof points in a horizontal direction; a half mirror that forces imaging light, which is incident through a lower imaging optical axis, to strike the camera; and a mirror that forces the imaging light, which is incident through an upper imaging optical axis, that is transmitted by the half mirror to strike the camera. The screen printing device is configured so as to have an upper illuminating part and a lower illuminating part, which individually illuminate each object to be imaged. Imaging light is captured by the camera after the upper illuminating part and the lower illuminating part have been individually operated in a mask imaging step and a substrate imaging step.