A sheet laminator includes a thermal fixing roller pair, a first heater, a second heater, multiple temperature detectors, and a driver. The thermal fixing roller pair includes a first thermal fixing roller and a second thermal fixing roller facing the first thermal fixing roller. The thermal fixing roller pair thermally fixes and conveys a two-ply sheet and a sheet medium nipped between two sheets of the two-ply sheet. The first heater heats the first thermal fixing roller. The second heater heats the second thermal fixing roller. The multiple temperature detectors are at different positions along an axial direction of the thermal fixing roller pair. The multiple temperature detectors detect a surface temperature of the thermal fixing roller pair. The driver drives the thermal fixing roller pair.