MEASUREMENT METHOD AND MEASUREMENT DEVICE

A charge potential distributed over a vehicle body (2A) resulting from the contact, separation, and friction between a tire (2B) and a road surface (3) is detected by a detecting unit (10) provided with a sensing electrode (11) that is disposed on the external surface of the vehicle body (2A), a reference electrode (12) that is disposed apart from the external surface of the vehicle body (2A) with a space therebetween, and a sensor amplifier (13) that senses a potential between the sensing electrode (11) and the reference electrode (13) as a signal and amplifies the signal. And the amplitude of the charge potential detected by the detecting unit (10) is monitored by a data processing unit (20), thereby making it possible to accurately identify not only the state of the road surface but also an internal pressure state of the tire, a wear state of the tire, and the like during vehicular travel.