PURPOSE: To provide an optometer which can distinguish between a measurement of the vision by the corrected eye and a measurement of the vision by the naked eye and which shortens measurement time of a person using a correction device.

CONSTITUTION: When the visual acuity of a subject who usually uses a correction device is measured in a state of the vision by the corrected eye, the subject doesn't depress a distinguish button 4 and target marks are sequentially displayed in accordance with a program. The subject responds to the mark by a response joy stick 3. A value of the visual acuity is determined in accordance with the error/correctness of the response and the value of visual acuity and the fact that the correction device is used are transferred to a computer 5 or a result display section. When it is measured in a state of the vision by the naked eye, the distinguish button 4 is depressed and the measurement is performed in accordance with another program and the value of visual acuity and the fact that the correction device is not used are transferred to the computer 5 or the result display section.