An on-board information display device can effectively display information by synchronizing a plurality of display units in accordance with information to be provided. The on-board information display device controls a plurality of display units, and includes an on-board information display controller including: a display-execution-processing determination unit that outputs a display-execution-processing determination result indicating whether parts or all of display screens to be displayed on the plurality of display units are to be synchronized, in accordance with on-board information to be displayed on the plurality of display units; and a display data generation unit that receives the display-execution-processing determination result and generates display data to allow the display screens to be displayed on the plurality of display units, in synchronization or without synchronization in accordance with the display-execution-processing determination result.