A control device comprising: a display control unit configured to cause display of a display unit to shift between a first display mode in which a first kind of image having a predetermined relation with an electric-to-electric image acquired by an imaging unit and a second kind of image different from the first kind of image are displayed and a second display mode in which the first kind of image is not displayed and the second kind of image is displayed, wherein the first kind of image is a through image acquired by an imaging unit and displayed in real time and the second kind of image is a reproduced image obtained by reproducing previously photographed still images or moving images; and a user interface configured to change the display of the images through one of a slide or scroll actions on a screen of the display unit or to cause an operation of an expansion of the reproduced image and contraction of the through image; characterized by a power control unit configured to reduce power supply to the imaging unit in the shift between the first and second display modes, wherein in the shift the display of the through image and the reproduced image is changed through one of the sliding action, scroll action, expansion of the reproduced image and contraction of the through image; wherein the power control unit is configured to control the reduction of the power supply to the imaging unit in said shift through one of said slide or scroll actions when a portion of the through image having a predetermined ratio, or more than said predetermined ratio, of the through image goes out of a first region set to correspond to a display region in the screen of the display unit; and wherein the power control unit is configured to control the reduction of the power supply to the imaging unit in said shift through said expansion of the reproduced image and contraction of the through image when a portion of the through image having a predetermined ratio, or more than said predetermined ratio, of the through image is shielded by the reproduced image. a display control unit configured to cause display of a display unit to shift between a first display mode in which a first kind of image having a predetermined relation with an electric-to-electric image acquired by an imaging unit and a second kind of image different from the first kind of image are displayed and a second display mode in which the first kind of image is not displayed and the second kind of image is displayed, wherein the first kind of image is a through image acquired by an imaging unit and displayed in real time and the second kind of image is a reproduced image obtained by reproducing previously photographed still images or moving images; and a user interface configured to change the display of the images through one of a slide or scroll actions on a screen of the display unit or to cause an operation of an expansion of the reproduced image and contraction of the through image; characterized by a power control unit configured to reduce power supply to the imaging unit in the shift between the first and second display modes, wherein in the shift the display of the through image and the reproduced image is changed through one of the sliding action, scroll action, expansion of the reproduced image and contraction of the through image; wherein the power control unit is configured to control the reduction of the power supply to the imaging unit in said shift through one of said slide or scroll actions when a portion of the through image having a predetermined ratio, or more than said predetermined ratio, of the through image goes out of a first region set to correspond to a display region in the screen of the display unit; and wherein the power control unit is configured to control the reduction of the power supply to the imaging unit in said shift through said expansion of the reproduced image and contraction of the through image when a portion of the through image having a predetermined ratio, or more than said predetermined ratio, of the through image is shielded by the reproduced image.