A posture estimation method includes calculating a posture change amount of an object based on an output of an angular velocity sensor, predicting posture information of the object by using the posture change amount, limiting a bias error in a manner of limiting a bias error component of an angular velocity around a reference vector in error information, and correcting the predicted posture information of the object based on the error information, the reference vector, and an output of a reference observation sensor. A posture estimation device for performing the method includes a posture-change amount calculation unit, a posture information prediction unit, an error information update unit, a bias error limitation unit, and a posture information correction unit.