A movable body circumstance monitoring apparatus includes element for capturing an image of a surrounding of a movable body depending upon movement of the movable body, deriving at least four feature points in a specified flat at the image, tracking the feature points in response to movement of the movable body from a first state to a second state, and specifying relative position and posture of the element for capturing the image at the first and second states in response to first flat coordinates of the feature points at the first state and second flat coordinates of the feature points at the second state based upon a tracking result.