A portable device configured to control a photography mode, comprising: a first camera unit configured to capture images; a second camera unit configured to capture images; and a processor configured to control the first camera unit and the second camera unit, wherein the processor is further configured to: detect first and second user's hands (210-1, 210-2) by using at least one of the first and second camera units; characterized in that the processor is further configured to: execute a 2D photography mode based on the detected first hand and the detected second hand if a first distance from the portable device to the first hand and a second distance from the portable device to the second hand are within a margin of error; detect that at least one of the first distance to the first hand and the second distance to the second hand is changed; and switch from the 2D photography mode to a 3D photography mode if detecting that a distance difference between the first and second distances is greater than a threshold distance, detect that the at least one of the first distance to the first hand and the second distance to the second hand is changed in a state where the 2D photography mode is switched to the 3D photography mode; and return to the 2D photography mode if detecting that the distance difference between the first and second distances is equal to or smaller than the threshold distance, wherein the 3D photography mode is a mode for generating a 3D image by using binocular parallax of the first and second camera units. a first camera unit configured to capture images; a second camera unit configured to capture images; and a processor configured to control the first camera unit and the second camera unit, wherein the processor is further configured to: detect first and second user's hands (210-1, 210-2) by using at least one of the first and second camera units; characterized in that the processor is further configured to: execute a 2D photography mode based on the detected first hand and the detected second hand if a first distance from the portable device to the first hand and a second distance from the portable device to the second hand are within a margin of error; detect that at least one of the first distance to the first hand and the second distance to the second hand is changed; and switch from the 2D photography mode to a 3D photography mode if detecting that a distance difference between the first and second distances is greater than a threshold distance, detect that the at least one of the first distance to the first hand and the second distance to the second hand is changed in a state where the 2D photography mode is switched to the 3D photography mode; and return to the 2D photography mode if detecting that the distance difference between the first and second distances is equal to or smaller than the threshold distance, detect first and second user's hands (210-1, 210-2) by using at least one of the first and second camera units; characterized in that the processor is further configured to: execute a 2D photography mode based on the detected first hand and the detected second hand if a first distance from the portable device to the first hand and a second distance from the portable device to the second hand are within a margin of error; detect that at least one of the first distance to the first hand and the second distance to the second hand is changed; and switch from the 2D photography mode to a 3D photography mode if detecting that a distance difference between the first and second distances is greater than a threshold distance, execute a 2D photography mode based on the detected first hand and the detected second hand if a first distance from the portable device to the first hand and a second distance from the portable device to the second hand are within a margin of error; detect that at least one of the first distance to the first hand and the second distance to the second hand is changed; and switch from the 2D photography mode to a 3D photography mode if detecting that a distance difference between the first and second distances is greater than a threshold distance, detect that the at least one of the first distance to the first hand and the second distance to the second hand is changed in a state where the 2D photography mode is switched to the 3D photography mode; and return to the 2D photography mode if detecting that the distance difference between the first and second distances is equal to or smaller than the threshold distance, wherein the 3D photography mode is a mode for generating a 3D image by using binocular parallax of the first and second camera units.