A sheet conveyor device may include a first portion configured to move, a cam configured to move in response to movement of the first portion, and a guide portion configured to move between first and second positions in response to the movement of the cam, to choose a first or second conveying path for a sheet. The cam may cause the guide portion to remain in position even if the first portion is moved a small amount, thereby helping to reduce the likelihood of paper jams arising from undesired movement of the guide portion.