An information processing device capable of processing navigation information, the information processing device comprising: a touch panel capable of displaying images and receiving a touch operation by a user; and a control section including a memory storing a computer program and a central processing unit configured to execute the computer program stored in the memory to cause the control section to function as an operation processing functional section and as an image generation section configured to generate a navigation image including a map image and a plurality of operation button images for receiving the touch operation, the images being displayed on the touch panel, wherein the operation button images include a first operation button image related to a navigation function and a second operation button image related to a plurality of functions other than the navigation function, wherein the image generation section is configured to generate a first image which is obtained by combining the navigation image and the first operation button image and a second image which includes the second operation button image, wherein the first image and the second image are respectively displayed in a first display region and a second display region, wherein the first display region and the second display region are separated by a boundary, wherein in response to the operation processing functional section detecting the touch operation by the user on a navigation button contained in the first operation button image, the image generation section is configured to move the boundary to enlarge a size of the first display region and to generate an image in which only the first display region is displayed over the entire touch panel, and wherein in the touch panel, a position of the first operation button image before the size of the first display region is enlarged is the same as a position of the first operation button image after the size of the first display region is enlarged, characterised in that the image generation section is configured to generate an animation image in which the boundary is gradually slid when moving the boundary, and the image generation section is further configured to generate the animation image such that an icon indicating the position of the information processing device on the map image of the navigation image is located at the center of the first display region while the boundary is gradually slid. a touch panel capable of displaying images and receiving a touch operation by a user; and a control section including a memory storing a computer program and a central processing unit configured to execute the computer program stored in the memory to cause the control section to function as an operation processing functional section and as an image generation section configured to generate a navigation image including a map image and a plurality of operation button images for receiving the touch operation, the images being displayed on the touch panel, wherein the operation button images include a first operation button image related to a navigation function and a second operation button image related to a plurality of functions other than the navigation function, wherein the image generation section is configured to generate a first image which is obtained by combining the navigation image and the first operation button image and a second image which includes the second operation button image, wherein the first image and the second image are respectively displayed in a first display region and a second display region, wherein the first display region and the second display region are separated by a boundary, wherein in response to the operation processing functional section detecting the touch operation by the user on a navigation button contained in the first operation button image, the image generation section is configured to move the boundary to enlarge a size of the first display region and to generate an image in which only the first display region is displayed over the entire touch panel, and wherein in the touch panel, a position of the first operation button image before the size of the first display region is enlarged is the same as a position of the first operation button image after the size of the first display region is enlarged, characterised in that the image generation section is configured to generate an animation image in which the boundary is gradually slid when moving the boundary, and the image generation section is further configured to generate the animation image such that an icon indicating the position of the information processing device on the map image of the navigation image is located at the center of the first display region while the boundary is gradually slid.