An obstacle detection apparatus and method which can detect the state of an obstacle according to a signal generated when the obstacle detection apparatus collides with the obstacle and a change in the posture of the obstacle detection apparatus caused due to the collision with the obstacle. The obstacle detection apparatus includes a main body which can be moved along the surface of the ground, a movement amount determination module which determines whether the amount of movement of the main body is outside a predefined threshold range, a posture determination module which determines the changed posture of the main body with respect to the surface of the ground according to the amount of movement of the main body, and a state determination module which determines the state of an obstacle based on the results of determination of the movement amount determination module or the posture determination module.