PROBLEM TO BE SOLVED: To appropriately calculate eye dimensions of an eye of a subject with eye diseases (for example a cataract eye) by improving an S/N ratio of an interference signal required for the measurement of eye dimensions.SOLUTION: An eye dimension measuring apparatus equipped with an interference optical system which irradiates the subjects eye with light emitted from a measurement light source and receives reflected light from the subjects eye as interfering light by a light receiving element and an operation processing unit for calculating the eye dimensions based on the light receiving signal of the light receiving element, a bandpass filter for extracting beat components out of the light receiving signal from the light receiving element, includes envelope detecting means for obtaining envelope signals of a beat signal output from the filter, and an envelope extracting filter which makes a signal having a prescribed frequency component corresponding to an envelope curve by the interference signal pass and blocks a signal of a frequency component exceeding the prescribed frequency out of the obtained envelope signals. The operation processing unit obtains the eye dimensions based on the interference signal extracted by the envelope extracting filter.
