A road entry system of a vehicle, comprising: a sensing unit configured to sense position information or movement information of an external obstacle located on a side or a rear of the vehicle, in response to the vehicle entering an entrance lane in an entrance zone from a narrow road to a wide road; wherein the sensing unit is further configured to sense the position information or the movement information of the external obstacle through a camera sensor or a radar sensor, or sense the position information or the movement information of the external obstacle by being connected to an infrastructure or an external vehicle that provides traffic information of the entrance lane via wireless communication; a determining unit configured to set a vehicle collision index calculated by numerically calculating the possibility of collision between the vehicle and the external obstacle based on the position information or the movement information of the external obstacle, and to determine that the entrance lane is congested in response to the vehicle collision index being greater than or equal to a preset value; and a control unit configured to control driving of the vehicle based on a result of the determining of whether the entrance lane is congested, wherein the control unit is further configured to limit a moving speed of the vehicle when the vehicle enters the entrance lane, in response to the determining unit determining that the entrance lane is congested; characterized in that, the sensing unit is further configured to sense the position information or the movement information of the external obstacle located on the side lane, in response to the determining unit determining that the entrance lane is congested after the vehicle enters the entrance lane, the determining unit is further configured to determine a traffic condition of a side lane based on the position information or the movement information of the external obstacle, as sensed by the sensing unit; and the control unit is further configured to control driving of the vehicle such that the vehicle enters the side lane while increasing a moving speed of the vehicle based on the position information or the movement information of the external obstacle, as sensed by the sensing unit, in response to determining that the traffic condition of the side lane is smooth. a sensing unit configured to sense position information or movement information of an external obstacle located on a side or a rear of the vehicle, in response to the vehicle entering an entrance lane in an entrance zone from a narrow road to a wide road; wherein the sensing unit is further configured to sense the position information or the movement information of the external obstacle through a camera sensor or a radar sensor, or sense the position information or the movement information of the external obstacle by being connected to an infrastructure or an external vehicle that provides traffic information of the entrance lane via wireless communication; a determining unit configured to set a vehicle collision index calculated by numerically calculating the possibility of collision between the vehicle and the external obstacle based on the position information or the movement information of the external obstacle, and to determine that the entrance lane is congested in response to the vehicle collision index being greater than or equal to a preset value; and a control unit configured to control driving of the vehicle based on a result of the determining of whether the entrance lane is congested, wherein the control unit is further configured to limit a moving speed of the vehicle when the vehicle enters the entrance lane, in response to the determining unit determining that the entrance lane is congested; characterized in that, the sensing unit is further configured to sense the position information or the movement information of the external obstacle located on the side lane, in response to the determining unit determining that the entrance lane is congested after the vehicle enters the entrance lane, the determining unit is further configured to determine a traffic condition of a side lane based on the position information or the movement information of the external obstacle, as sensed by the sensing unit; and the control unit is further configured to control driving of the vehicle such that the vehicle enters the side lane while increasing a moving speed of the vehicle based on the position information or the movement information of the external obstacle, as sensed by the sensing unit, in response to determining that the traffic condition of the side lane is smooth.