A parking assist apparatus for assisting parallel parking of an own vehicle to a target parking position, the parking apparatus comprising: a first route calculation unit configured to calculate a first route for moving the own vehicle to a virtual departure position where a predetermined portion of the own vehicle is separated from a front obstacle by a predetermined distance and the own vehicle is to assist get out from the target parking position based on a parking space and a constraint condition of own vehicle behavior; a second route calculation unit configured to calculate a second route for moving the own vehicle from an initial position where parking assistance is started to the virtual departure position; and a parking route setting unit configured to set a parking route of the own vehicle with use of the first route and the second route, wherein the second route calculation unit comprises: a forward/backward movement determination unit configured to determine whether the initial position is in front or in rear in a parking direction with respect to a first reference line extending along a longitudinal direction of the own vehicle at the virtual departure position, wherein the first reference line is passing through a center of the own vehicle; a backward movement starting route calculation unit configured to calculate a backward movement starting route that connects from the initial position to the virtual departure position by a backward movement of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in front in the parking direction with respect to the first reference line; and a forward movement starting route calculation unit configured to calculate a forward movement starting route that connects from the initial position to the virtual departure position by forward and backward movements of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in rear in the parking direction with respect to the first reference line or when it is impossible to calculate the backward movement starting route by the backward movement starting route calculation unit. a first route calculation unit configured to calculate a first route for moving the own vehicle to a virtual departure position where a predetermined portion of the own vehicle is separated from a front obstacle by a predetermined distance and the own vehicle is to assist get out from the target parking position based on a parking space and a constraint condition of own vehicle behavior; a second route calculation unit configured to calculate a second route for moving the own vehicle from an initial position where parking assistance is started to the virtual departure position; and a parking route setting unit configured to set a parking route of the own vehicle with use of the first route and the second route, wherein the second route calculation unit comprises: a forward/backward movement determination unit configured to determine whether the initial position is in front or in rear in a parking direction with respect to a first reference line extending along a longitudinal direction of the own vehicle at the virtual departure position, wherein the first reference line is passing through a center of the own vehicle; a backward movement starting route calculation unit configured to calculate a backward movement starting route that connects from the initial position to the virtual departure position by a backward movement of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in front in the parking direction with respect to the first reference line; and a forward movement starting route calculation unit configured to calculate a forward movement starting route that connects from the initial position to the virtual departure position by forward and backward movements of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in rear in the parking direction with respect to the first reference line or when it is impossible to calculate the backward movement starting route by the backward movement starting route calculation unit. a forward/backward movement determination unit configured to determine whether the initial position is in front or in rear in a parking direction with respect to a first reference line extending along a longitudinal direction of the own vehicle at the virtual departure position, wherein the first reference line is passing through a center of the own vehicle; a backward movement starting route calculation unit configured to calculate a backward movement starting route that connects from the initial position to the virtual departure position by a backward movement of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in front in the parking direction with respect to the first reference line; and a forward movement starting route calculation unit configured to calculate a forward movement starting route that connects from the initial position to the virtual departure position by forward and backward movements of the own vehicle as the second route when the forward/backward movement determination unit determines that the initial position is in rear in the parking direction with respect to the first reference line or when it is impossible to calculate the backward movement starting route by the backward movement starting route calculation unit.