PURPOSE : An online building appraisal system and a method thereof are provided to divide lands having the same representative unique properties into the same price zone and facilitate a precise appraisal which reflects the unique detail property of an individual land. CONSTITUTION : A specimen management unit (150) manages one or more specimen prices for a specimen having one or more representative unique properties corresponding to a predetermined condition. The specimen is located in an investigation object area and is classified into a use district and a use situation. A representative unique property management unit (120) manages a temporary land, which is classified into one or more representative unique properties. A same price zone management unit (140) manages one or more temporary lands by classifying the same into the same price zone which includes one or more specimens. A price calculation unit (160) manages a land property comparison table and calculates the price of a land by applying a property value using the land property comparison table to the specimen price of a specimen in the same price zone. The specimen management unit is a set of as apartment house property information and manages the specimen and the specimen price of an apartment house. The price calculation unit calculates building prices by applying repurchase costs and a rate of depreciation to a set of building feature information. [Reference numerals] (110) Real property data management unit; (120) Representative unique property management unit; (130) Real property data verifying unit; (140) Same price zone management unit; (150) Specimen management unit; (160) Price calculation unit; (170) Communication unit; (200) User terminal; (300) External information providing unit; (6) Examiner terminal