A length measurement device comprises: a tape which is wound on a reel received in a case, one end of which is pulled out of the case so as to measure the length of an object, and which has a barcode formed on one surface thereof; a first measurement unit for recognizing the barcode on the tape so as to generate a first measurement value of the length along which the tape is pulled out of the case; a second measurement unit for sensing a rotation angle of the reel so as to generate a second measurement value of the length along which the tape is pulled out of the case; and a control unit for making the first measurement value and the second measurement value mutually compensate for each other so as to convert same into the pulled-out length information of the tape.