A three-dimensional retina image generator, comprising: a first light source unit that has a first light source; a light divider that divides an output light beam output from the first light source into an object-scanning light beam that is delivered to a retina of an eye ball and a reference light beam for reference; a reference light beam unit into which the reference light beam is input and that causes the input reference light beam to reflect as a reference reflection light beam; a measurement unit that is configured to scan the object-scanning light beam over the retina and that causes light scattered at the retina to reflect as an object-reflected light beam; in interference intensity detector (150, 154) that generates an interference light beam in which the reference reflection light beam and the object-reflected light beam are caused to interfere with each other and that detects an interference intensity for each wavelength in the generated interference light beam; a generator that generates a three-dimensional image of the retina based on the detected interference intensity for each wavelength; a second light source unit that has a second light source for outputting a line beam and that outputs the line beam in order to transmit the line beam in a path identical to that of the object-scanning light beam in the measurement unit; and a positional displacement detector that has a line sensor, that detects the line beam reflected from the retina and output from the measurement unit by the line sensor and that calculates the amount of movement of the retina from the amount of detected scanning position displacement during scanning of the retina with the object-scanning light beam based on the detected line beam, characterized in that the measurement unit further comprises: a single scanning mirror that adjusts scanning positions when the line beam and the object-scanning light beam scan the retina; and a controller that controls the movement of the single scanning mirror, and wherein the controller controls the positions of the scanning mirror to control the irradiation directions of the line beam and the object-scanning light beam during scanning of the retina with single scanning mirror based on the detected scanning position displacement. a first light source unit that has a first light source; a light divider that divides an output light beam output from the first light source into an object-scanning light beam that is delivered to a retina of an eye ball and a reference light beam for reference; a reference light beam unit into which the reference light beam is input and that causes the input reference light beam to reflect as a reference reflection light beam; a measurement unit that is configured to scan the object-scanning light beam over the retina and that causes light scattered at the retina to reflect as an object-reflected light beam; in interference intensity detector (150, 154) that generates an interference light beam in which the reference reflection light beam and the object-reflected light beam are caused to interfere with each other and that detects an interference intensity for each wavelength in the generated interference light beam; a generator that generates a three-dimensional image of the retina based on the detected interference intensity for each wavelength; a second light source unit that has a second light source for outputting a line beam and that outputs the line beam in order to transmit the line beam in a path identical to that of the object-scanning light beam in the measurement unit; and a positional displacement detector that has a line sensor, that detects the line beam reflected from the retina and output from the measurement unit by the line sensor and that calculates the amount of movement of the retina from the amount of detected scanning position displacement during scanning of the retina with the object-scanning light beam based on the detected line beam, characterized in that the measurement unit further comprises: a single scanning mirror that adjusts scanning positions when the line beam and the object-scanning light beam scan the retina; and a controller that controls the movement of the single scanning mirror, and a single scanning mirror that adjusts scanning positions when the line beam and the object-scanning light beam scan the retina; and a controller that controls the movement of the single scanning mirror, and wherein the controller controls the positions of the scanning mirror to control the irradiation directions of the line beam and the object-scanning light beam during scanning of the retina with single scanning mirror based on the detected scanning position displacement.