In an axial misalignment determination apparatus mounted on a mobile object, a misalignment determiner performs axial misalignment determination processing to determine whether or not a reference axis of a transceiver for transmitting and receiving probe waves and a mounting reference axis of the mobile object coincide in direction. A necessity determiner determines whether or not a condition for performing the axial misalignment determination processing is met, and if the condition is met, determines that there is a need to perform the axial misalignment determination processing.The condition is predefined based on an extrapolation result of an extrapolator for extrapolating a target and a determination result of a deposit determiner for determining the presence or absence of a deposit on an object. If it is determined by the necessity determiner that there is a need to perform the axial misalignment determination processing, the misalignment determiner performs the axial misalignment determination processing.