There is provided a display device of an air jet loom (1) that includes a weft insertion device (2) causing a weft yarn (Y) released from a weft measuring and storing device (11) to move by compressed air injected from a main nozzle (7) and plural sub-nozzles (5) arranged in the direction of weft insertion, a setting and measuring device (21, 24, 28, 29, 37, 45) that serves to set and measure pressure or flow rate of the main nozzle (7) and also to set and measure pressure of the sub nozzle (5), and a controller (47) storing the measured pressure or flow rate of the main nozzle (7) and equipped with a display (61). The controller (47) causes the display (61) to show a line graph (63) representing pressure or flow rate of the main nozzle (7) with which weft insertion is completed at a previously set angular position of the air jet loom (1) for each of different predetermined pressures of the sub-nozzle (5).