According to one embodiment, an onboard camera automatic calibration apparatus includes at least a road surface point selection unit, an amount-of-rotation-around-Z-axis calculation unit and a coordinate rotation correction unit. The road surface point selection unit selects multiple points not less than three on a road surface in a predetermined image among the multiple images obtained by an onboard camera and selects multiple combinations of two points from among the multiple points. The amount-of-rotation-around-Z-axis calculation unit determines, in a camera coordinate system with an optical axis as a Z axis, an amount of rotation around the Z axis such that the road surface is parallel to an X axis, based on the multiple combinations and motion vectors. The coordinate rotation correction unit performs rotation correction around the Z axis for the images obtained by the onboard camera based on the determined amount of rotation around the Z axis.