This paper outlines the method of measurement for strain of concrete and the results of Young's modulus at the ages of one to twenty-eight days.
　Strain for concrete specimens (φ10x20, φ15x30cm) were measured with strain gauges compresso-meter and deformation between the loading plates of testing machine. Test results indicated that the method used with strain gauge possessed higher accuracy then other methods and paraffin was valid adhensive material for strain gauges at the age of one day instead of resin materials.
　Young's modulus of concrete defined with secant modulus and code modulus was calculated on the virgin stress-strain curve. At the ages of fourteen days to twenty-eight days, concrete had the larger inceasing ratio of compressive strength compared to that of Young's modulus. On the contrary, it is conceivable that Young's modulus increased at the same degree as compressive srength up to approximately seven days.