A parking assistance device for assisting in parking a vehicle in a parking space that is provided on one side of a road, the parking assistance device being configured to compute a first parking path for starting moving the vehicle forward from an initial position of the vehicle, and a second parking path for starting moving the vehicle backward from the initial position of the vehicle, select one of the first parking path or the second parking path on the basis of a preset evaluation function, and set the selected path as a parking path to be used, characterized in that the parking assistance device further comprises: a pull-out path computing unit configured to compute a pull-out path for pulling the vehicle out of the parking space on the basis of information on the parking space and constraint conditions regarding vehicle behavior; a candidate connection position setting unit configured to set a plurality of candidate connection positions on the pull-out path computed by the pull-out path computing unit; a reachable path computing unit configured to compute a forward drive start path for starting moving the vehicle forward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions, and a reverse drive start path for starting moving the vehicle backward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions; a parking path computing unit configured to compute the first parking path by connecting the forward drive start path and the pull-out path at a first park-out position (B 1) that is one of the plurality of candidate connection positions reachable along the forward drive start path, and compute the second parking path by connecting the reverse drive start path and the pull-out path at a second park-out position that is one of the plurality of candidate connection positions reachable along the reverse drive start path; and a path selection unit configured to select one of the first parking path or the second parking path on the basis of the evaluation function. compute a first parking path for starting moving the vehicle forward from an initial position of the vehicle, and a second parking path for starting moving the vehicle backward from the initial position of the vehicle, select one of the first parking path or the second parking path on the basis of a preset evaluation function, and set the selected path as a parking path to be used, characterized in that the parking assistance device further comprises: a pull-out path computing unit configured to compute a pull-out path for pulling the vehicle out of the parking space on the basis of information on the parking space and constraint conditions regarding vehicle behavior; a candidate connection position setting unit configured to set a plurality of candidate connection positions on the pull-out path computed by the pull-out path computing unit; a reachable path computing unit configured to compute a forward drive start path for starting moving the vehicle forward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions, and a reverse drive start path for starting moving the vehicle backward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions; a parking path computing unit configured to compute the first parking path by connecting the forward drive start path and the pull-out path at a first park-out position (B 1) that is one of the plurality of candidate connection positions reachable along the forward drive start path, and compute the second parking path by connecting the reverse drive start path and the pull-out path at a second park-out position that is one of the plurality of candidate connection positions reachable along the reverse drive start path; and a path selection unit configured to select one of the first parking path or the second parking path on the basis of the evaluation function. a pull-out path computing unit configured to compute a pull-out path for pulling the vehicle out of the parking space on the basis of information on the parking space and constraint conditions regarding vehicle behavior; a candidate connection position setting unit configured to set a plurality of candidate connection positions on the pull-out path computed by the pull-out path computing unit; a reachable path computing unit configured to compute a forward drive start path for starting moving the vehicle forward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions, and a reverse drive start path for starting moving the vehicle backward from the initial position of the vehicle to allow the vehicle to reach at least one of the plurality of candidate connection positions; a parking path computing unit configured to compute the first parking path by connecting the forward drive start path and the pull-out path at a first park-out position (B 1) that is one of the plurality of candidate connection positions reachable along the forward drive start path, and compute the second parking path by connecting the reverse drive start path and the pull-out path at a second park-out position that is one of the plurality of candidate connection positions reachable along the reverse drive start path; and a path selection unit configured to select one of the first parking path or the second parking path on the basis of the evaluation function.