PROBLEM TO BE SOLVED: To accurately estimate whether a driver is in a state suitable for driving.SOLUTION: A driver state estimation method includes: measuring a brain wave of a driver (S101); and estimating whether the driver is in a state suitable for driving depending on the brain wave when detecting a drive operation of the driver (S105 to S107).SELECTED DRAWING: Figure 2【課題】運転者が運転に適した状態にあるか否かを、精度よく推定する。【解決手段】運転者の脳波を計測しておき(S101)、運転者の運転操作を検出したときの脳波に応じて、運転者が運転に適した状態にあるか否かを推定する(S105~S107)。【選択図】図2