A medical image diagnostic apparatus that includes an operation terminal having an input device and a display device, the medical image diagnostic apparatus comprising: an application execution state detecting unit configured to detect an execution state of an application serving as application execution state information; a screen saver shape storing unit configured to store shapes of a screen saver corresponding to execution states of the application; a screen saver activation event detecting unit configured to detect an event serving as an activation condition for the screen saver; a screen saver screen creating unit configured to read the shape of the screen saver corresponding to the execution state of the application from the screen saver shape storing unit and to create screen saver image information for causing the display device to display the screen saver on the screen of the display device on the basis of the shape of the screen saver read from the screen saver shape storing unit; and a screen saver managing unit configured to receive a notification indicating that the event serving as the activation condition for the screen saver is detected from the screen saver activation event detecting unit and to request the application execution state detecting unit to detect the execution state of the application and to receive the application execution state information detected by the application execution state detecting unit and to give the application execution state information to the screen saver screen creating unit to request the screen saver screen creatingunit to create the screen saver image information, wherein the screen saver managing unit is configured to receive a cancellation condition for the screen saver, to cause the display device to display an authentication screen by giving authentication screen information to the display device, to perform authentication using authentication information of a user received from the input device, and to give a non-display request for the screen saver to the screen saver screen creating unit only when the authentication is successful, characterized in that the shapes of the screen saver stored by the screen saver shape storing unit correspond to divided areas of the screen of the display device. an application execution state detecting unit configured to detect an execution state of an application serving as application execution state information; a screen saver shape storing unit configured to store shapes of a screen saver corresponding to execution states of the application; a screen saver activation event detecting unit configured to detect an event serving as an activation condition for the screen saver; a screen saver screen creating unit configured to read the shape of the screen saver corresponding to the execution state of the application from the screen saver shape storing unit and to create screen saver image information for causing the display device to display the screen saver on the screen of the display device on the basis of the shape of the screen saver read from the screen saver shape storing unit; and a screen saver managing unit configured to receive a notification indicating that the event serving as the activation condition for the screen saver is detected from the screen saver activation event detecting unit and to request the application execution state detecting unit to detect the execution state of the application and to receive the application execution state information detected by the application execution state detecting unit and to give the application execution state information to the screen saver screen creating unit to request the screen saver screen creatingunit to create the screen saver image information, wherein the screen saver managing unit is configured to receive a cancellation condition for the screen saver, to cause the display device to display an authentication screen by giving authentication screen information to the display device, to perform authentication using authentication information of a user received from the input device, and to give a non-display request for the screen saver to the screen saver screen creating unit only when the authentication is successful, characterized in that the shapes of the screen saver stored by the screen saver shape storing unit correspond to divided areas of the screen of the display device.