A hearing aid that analyzes a surrounding acoustic environment and automatically switches between a plurality of hearing aid processing reduces noise by limiting directionality, when the user is in a noisy outdoor location. However, in the case where directionality is limited to the front when the user is walking or the like, the user is put in extreme danger because he/she cannot notice sound of danger approaching from behind. Behavior analysis of identifying a walking state of the user is necessary in addition to environmental analysis, but typical walking detection using a sensor as in the case of a pedometer and the like is not applicable to a device worn at an ear such as a hearing aid. On the basis of an occurrence pattern of wind noise when walking, the walking state of the user is identified in the case where pulse-like wind noise occurs repeatedly. This enables walking detection to be performed using an existing structure, with there being no need to provide a sensor or the like. Hence, it is possible to provide a hearing aid that can be safely used even outdoors.