NAUTICAL CHART DISPLAY DEVICE, NAUTICAL CHART DISPLAY METHOD, PROGRAM, AND OBSERVATION AUXILIARY TOOL

Provided is a chart display device capable of easily partially confirming a chart. A chart display device includes with a display unit to display the chart on a screen, a touch position detection unit to detect a touched position of the screen, an operation auxiliary tool determination unit to determine whether an operation auxiliary tool having detected elements to be detected by the touch position detection unit is placed on the screen, an area specification unit to specify a corresponding area corresponding to the operation auxiliary tool in the chart based on the position of the detected elements, and an operation reception unit to receive an operation for the corresponding area in the chart.