A method of measuring physical strength of a subject and an apparatus therefor in which the maximum oxygen uptake based on 75% of the estimated maximum heart rate as a reference is estimated to thereby evaluate physical strength based on the oxygen uptake during exercise. The oxygen uptake is used as an index for evaluating physical strength, and VO2@75%HRmax, which is oxygen uptake measured at 75% of estimated maximum heart rate, is used as a reference so that comparison can be made safely with a measured value even for middle and high ages. The apparatus is provided with a load device (3) which can give a ramp load to a subject (e.g. 15 W/min to male and 10 W/min to female), a pulse rate detecting device (2,13) which can measure pulse rate successively in the duration in which the load is given to the subject, and a device (10) for averaging the measured pulse rate and the value of the given load over small time periods, subjecting the value of the pulse rate relative to the value of the load to straight line regression, and calculating the slope A and offset B of the resulting straight line.