A method for memory training using brain stimulation, the method comprising: displaying, by a computer, a first problem on a task display portion of a screen, wherein the task display portion is an area where output image being a task is provided on the screen, wherein the first problem comprises one or more output images to be displayed at a specific location within the task display portion, characterized by further comprising: receiving, by the computer, a first response corresponding to the first problem, wherein the first response comprises a result of comparing a previous first problem that was displayed before N times of executing the method, with the displayed first problem and wherein N is a natural number; displaying, by the computer, a second problem on a central portion of the screen; and receiving, by the computer, a second response corresponding to the second problem, wherein the second problem is provided to the user so as to watch a center of an output picture, wherein the first response is to enter whether a currently provided screen image is the same as a screen image before 'N' times, wherein the screen image comprises one or more task display portions, and wherein the computer determines that the first response is not a suitable answer when the second response is not received, and wherein the computer performs the memory training again when a correct answer rate of the second problem is lower than a specific value, wherein the computer provides the first problem on a screen of a head-mounted display device, and wherein the displaying the first problem comprises: determining a location in a three-dimensional space including the output images of the first problem, based on an arrangement location of the second problem displayed in the three-dimensional space, and wherein the displaying the first problem further comprises: measuring, by the head-mounted display device, a gaze direction of the user by recognizing a head movement of the user; and determining arrangement locations of the output images to be displayed as the first problem, based on the gaze direction. receiving, by the computer, a first response corresponding to the first problem, wherein the first response comprises a result of comparing a previous first problem that was displayed before N times of executing the method, with the displayed first problem and wherein N is a natural number; displaying, by the computer, a second problem on a central portion of the screen; and receiving, by the computer, a second response corresponding to the second problem, wherein the second problem is provided to the user so as to watch a center of an output picture, wherein the first response is to enter whether a currently provided screen image is the same as a screen image before 'N' times, wherein the screen image comprises one or more task display portions, and wherein the computer determines that the first response is not a suitable answer when the second response is not received, and wherein the computer performs the memory training again when a correct answer rate of the second problem is lower than a specific value, wherein the computer provides the first problem on a screen of a head-mounted display device, and wherein the displaying the first problem comprises: determining a location in a three-dimensional space including the output images of the first problem, based on an arrangement location of the second problem displayed in the three-dimensional space, and wherein the displaying the first problem further comprises: measuring, by the head-mounted display device, a gaze direction of the user by recognizing a head movement of the user; and determining arrangement locations of the output images to be displayed as the first problem, based on the gaze direction. determining a location in a three-dimensional space including the output images of the first problem, based on an arrangement location of the second problem displayed in the three-dimensional space, and wherein the displaying the first problem further comprises: measuring, by the head-mounted display device, a gaze direction of the user by recognizing a head movement of the user; and determining arrangement locations of the output images to be displayed as the first problem, based on the gaze direction. measuring, by the head-mounted display device, a gaze direction of the user by recognizing a head movement of the user; and determining arrangement locations of the output images to be displayed as the first problem, based on the gaze direction.