PROBLEM TO BE SOLVED: To provide a power assist device for performing power assist that hardly gives a sense of discomfort to an operator, and a walking aid vehicle using the same.SOLUTION: In a power assist device 110, control means 80 detects a periodically varying component of operation force due to a motion of an operator on the basis of a history of the operation force detected by operation force detection means 70, a component due to the motion of the operator of a current operation force is calculated from a waveform and frequency of the periodically varying component of the operation force, a correction value is calculated in which the calculated component due to the motion of the operator of the current operation force is excluded from the current operation force, and power means 90 is controlled so that power assist force calculated on the basis of the correction value is output as power.【課題】操作者が違和感を覚えにくいパワーアシスト行うパワーアシスト装置及びそれを用いた歩行補助車を提供する。【解決手段】制御手段８０が、操作力検出手段７０が検出した操作力の履歴に基づいて、操作者の動作に起因した操作力の周期的に変動する成分を検出し、操作力の周期的に変動する成分の波形と周波数から現在の操作力の操作者の動作に起因する成分を算出し、現在の操作力から前記算出した現在の操作力の操作者の動作に起因する成分を除いた補正値を算出し、補正値に基づいて算出したパワーアシスト力を動力として出力するように動力手段９０を制御するパワーアシスト装置１１０。【選択図】図２
