A mechanical amplification device includes a three-dimensional knitted material and foam bodies and laminated in the periphery of the three-dimensional knitted material. A mechanical amplification device provided with a film is disposed between the three-dimensional knitted material and the foam bodies and is provided, and a vibration sensor is attached to this mechanical amplification device. Micro vibration on the body surface caused by a human biological signal is propagated to the foam bodies, the film, and the three-dimensional knitted material, and membrane vibration is generated in the foam bodies and the film, while string vibration of a fiber is generated in the three-dimensional knitted material. As a result, the biological signal such as heart rate, respiration, atrial and aortic vibrations and the like can be accurately transmitted.