1. A three-dimensional display device comprising: display section for carrying out three-dimensional display based on two or more two-dimensional images having parallax therebetween; digital zoom section for digitally zooming the two-dimensional images; zoom rate obtaining section for obtaining a digital zoom rate of the two-dimensional images zoomed by the digital zoom section; parallax modifying section for modifying at least one of the digitally zoomed two-dimensional images based on an enlarged amount of parallax to provide an amount of parallax between the digitally zoomed two-dimensional images equal to the enlarged amount of parallax when the digital zoom rate obtained by the zoom rate obtaining section is larger than 100%, wherein the enlarged amount of parallax is obtained by enlarging, at a moderated digital zoom rate, an amount of parallax between the two-dimensional images before being digitally zoomed, the moderated digital zoom rate is obtained by moderating the digital zoom rate at a moderation rate, and the moderation rate increases as the zoom rate increases; and display control section for causing the display section to carry out three-dimensional display based on the modified two-dimensional images.