Abstract: This optical dendrometer with a telescope(2.4x)attached consists of two identicaleircular wedge-prisms,a pair of penta-prism and a circular hypsometer.It is small size,light weight and inexpensive.This instrument is capable of measuring upperdiamter of a stem,distance,height,etc.Although base rule(a variable base line)of the dendrometer is only 300 mm.the measurement of diameter may be widened to three meters and height lengthened to sixty meters by means of counter-rotating the pair of wedge-prism.The technical identification committee checked the accuracy and approved satisfactorily.