A mobile terminal comprising: a first camera configured to capture a left-eye image for generating a 3D image; a second camera configured to capture a right-eye image for generating the 3D image; a display unit configured to display the 3D image generated based on the left-eye image and the right-eye image; and a controller configured to: determine an extent of a 3D effect on at least one object included in the 3D image, control the display unit to display information indicating the determined extent of the 3D effect, wherein the information indicates at least one of an optimal state of the 3D effect for the at least one object, an excessive state of the 3D effect for the at least one object, and an absence of the 3D effect for the at least one object, control the display unit to display the information at a corresponding position of the at least one object within the 3D image, determine the extent of the 3D effect of the at least one object in the 3D image each time each frame of the 3D image changes, and modify a display style of the information by real time to indicate the extent of the 3D effect based on the determined extent of the 3D effect, characterized in that the controller is further configured to: cut a specific object, for which the state of the 3D effect is non optimal, in a current frame of the 3D image; and replace the cut object in the current frame of the 3D image by synthesizing a 3D effect from a part of a previous frame, wherein the part in the previous frame corresponds to the cut object in the current frame and the part having an optimal state of the 3D effect. a first camera configured to capture a left-eye image for generating a 3D image; a second camera configured to capture a right-eye image for generating the 3D image; a display unit configured to display the 3D image generated based on the left-eye image and the right-eye image; and a controller configured to: determine an extent of a 3D effect on at least one object included in the 3D image, control the display unit to display information indicating the determined extent of the 3D effect, wherein the information indicates at least one of an optimal state of the 3D effect for the at least one object, an excessive state of the 3D effect for the at least one object, and an absence of the 3D effect for the at least one object, control the display unit to display the information at a corresponding position of the at least one object within the 3D image, determine the extent of the 3D effect of the at least one object in the 3D image each time each frame of the 3D image changes, and modify a display style of the information by real time to indicate the extent of the 3D effect based on the determined extent of the 3D effect, determine an extent of a 3D effect on at least one object included in the 3D image, control the display unit to display information indicating the determined extent of the 3D effect, wherein the information indicates at least one of an optimal state of the 3D effect for the at least one object, an excessive state of the 3D effect for the at least one object, and an absence of the 3D effect for the at least one object, control the display unit to display the information at a corresponding position of the at least one object within the 3D image, determine the extent of the 3D effect of the at least one object in the 3D image each time each frame of the 3D image changes, and modify a display style of the information by real time to indicate the extent of the 3D effect based on the determined extent of the 3D effect, characterized in that the controller is further configured to: cut a specific object, for which the state of the 3D effect is non optimal, in a current frame of the 3D image; and replace the cut object in the current frame of the 3D image by synthesizing a 3D effect from a part of a previous frame, wherein the part in the previous frame corresponds to the cut object in the current frame and the part having an optimal state of the 3D effect. cut a specific object, for which the state of the 3D effect is non optimal, in a current frame of the 3D image; and replace the cut object in the current frame of the 3D image by synthesizing a 3D effect from a part of a previous frame, wherein the part in the previous frame corresponds to the cut object in the current frame and the part having an optimal state of the 3D effect.