An image display device includes a first inertial sensor, an imaging section, and a calculation section. The calculation section calculates a first spatial relationship between the marker and the imaging section in the case where the imaging section captures an image of a marker presented by a device including a second inertial sensor, and calculates a second spatial relationship between the imaging section and the first inertial sensor based at least on the first spatial relationship, first data and second data, the first data including a first orientation of the first inertial sensor and the second data including a second orientation of the second inertial sensor respectively obtained from the first inertial sensor and the second inertial sensor.