When very impulsive wave force act on the structure, the response of the measuring system brings forth complicated problems. In this note, the response time profiles of single and two degree-of-freedom systems to various shock pulses are presetned by the calculations, and the estimation method of the exciting shock from the response time history is investigated. Such a method is called Response-Input Conversion.
　The Response-Input Conversion can be made by the following procedures:
(1) To resolve the response time history into the Fourier series having a fundamental period enough to almost disregard the residual response amplitude.
(2) To modify the amplitude and the phase of each fourier component by the amplification factor and the phase angle respectively which are given by the steady state solution of the vibration equation to a harmonic excitation.
(3) To composite the modified Fourier componenets.
　The aplication of the Response-Input Conversion to the response time history for various shock pulse establishes that the finally composited time history almost coincides with the original shock pulse.
　Two analogue divices, the low-pass filter and the Response-Input Converter, as a simple and easy method are also tested to a single-freedom-system.