An in-vehicle driving assistance apparatus that can execute driving assistance on the basis of any one of a plurality of control modes having mutually-different degrees of driving assistance, the apparatus comprising a receiving unit configured to receive a transition instruction of the control mode, a setting unit configured to set the control mode based on the transition instruction, a determining unit configured to determine whether or not a transition scheme for the control mode indicated by the transition instruction has a pre-registered detail, and a suppressing unit configured to suppress the setting of the control mode by the setting unit when the transition scheme for the control mode indicated by the transition instruction does not have the pre-registered detail.