A medium conveying apparatus includes an imaging device to image a medium and configured to move in a moving direction, a roller configured to move in the moving direction, on an upstream side of the imaging device, a conveyance guide provided with the imaging device to move the imaging device, wherein the conveyance guide includes a slope for coming into contact with the medium, an engaging member provided with the imaging device to move the imaging device, and a moving member to move the imaging device by engaging with the engaging member in conjunction with a movement of the roller. The engaging member and the moving member are configured to be separated at a distance from one another when the medium is not conveyed. The moving member moves the imaging device by engaging with the engaging member only when the medium has a thickness greater than the distance.