Peak hold device, impedance measurement device, metal deposition detection device, and battery internal temperature estimation device

A peak hold device, wherein

• the peak hold device acquires a peak value of any maximum peak or minimum peak included in a damped oscillation waveform, and
• the peak hold device uses the maximum peak or the minimum peak as a target peak from which to acquire the peak value, and for a plurality of damped oscillation waveforms, repeats a process of starting to hold a damped oscillation waveform value at a time before the target peak, and ceasing to hold the damped oscillation waveform value at a time after the target peak.