A sheet separator including two guides disposed to face each other across a distance in a width direction, at least one of the two guides being configured to move along the width direction to enlarge or reduce the distance therebetween, a separation roller, a separation pad configured to separate sheets being conveyed by the separation roller on a sheet-by-sheet basis in cooperation with the separation roller, a pressing mechanism configured to apply a pressing load to press the separation pad toward the separation roller, and an adjuster configured to increase the pressing load in response to the at least one of the two guides moving in a direction to enlarge the distance, and decrease the pressing load in response to the at least one of the two guides moving in a direction to reduce the distance.