Frailty is common among the elderly, it represents a state of the sharp decline in physical function. Because it is in the middle of health and care, delaying the onset of frailty can extend healthy life expectancy and reduce the medical burden on society. Currently, in the diagnostic criteria(J-CHS) for early detection of frailty, deterioration in physical ability is judged solely by walking speed in lower limb function. This paper a gait measuring system based on the Six-Minute Walk Test(6MWT) is constructed and a novel method for more objectively evaluating the state of physical frailty is proposed. The gait measurement system only requires subjects to wear a wearable inertial acceleration sensor behind each ankle and walk with a fast speed for six minutes. PC or smartphone receives the gait data from the sensors and automatically processes it to extract walking parameters such as stride length, cadence, and walking velocity. In this evaluation system, the stride length and cadence are used to diagnose frailty instead of the current method which is only using walking speed, and the pre-frailty state is represented more detailly.