1. An image display apparatus, comprising: a display unit that displays a first image contained in a first image group of an inside of a subject and a second image contained in a second image group of the inside of the subject, the first image group and the second image group being picked up respectively by a first imaging device and a second imaging device that are included in a multiple-lens capsule endoscope; a control unit that extracts a related image related to a currently displayed image currently displayed in the display unit from the first and second image groups to make the display unit display the related image extracted; a storage unit that stores default data in which a time difference between an imaging time of the first image and an imaging time of the second image is set differently for each site inside the subject; and a setting unit that obtains the default data from the storage unit and sets, for a site inside of the subject to be displayed, the time difference for the corresponding site of the default data; wherein the control unit switches the time difference for each site inside the subject based on the default data and performs control to synchronously display the first image and the second image having the time difference set for each site inside the subject in respective display areas on the display unit.