The present disclosure provides a lane estimating apparatus and method. The apparatus includes: a lane determiner, an obstacle position calculator, a vehicle position corrector, and a lane estimator. The lane determiner compares a first lane detected by a first sensor with a lane on an actual road or a second lane on a local map to determine reliability of the first lane. The obstacle position calculator detects, when the reliability of the detected first lane is less than a preset reference, a first obstacle in the vicinity of a vehicle and a second obstacle on the local map, and calculates a difference between slopes and positions of straight lines extracted from the first obstacle and the second obstacle. The vehicle position corrector corrects a heading direction and a position of the vehicle based on the difference between the slopes and positions of the straight lines. In addition, the lane estimator estimates a driving lane on the local map.