Disclosed herein is an apparatus for adjusting the height of a saddle for a bicycle. The apparatus includes a saddle lift device that moves the saddle upwards or downwards to adjust the height of the saddle, and a controller that controls the operation of the saddle lift device. In the present invention, even when a bicycle is traveling, the height of the saddle can be automatically adjusted to an appropriate height depending on the travel conditions, thus enhancing the safety of a rider and providing convenience. Moreover, the present invention stores information about the body type of the rider and automatically adjusts the height of the saddle to a height suitable for the body type, thus making it markedly easy to adjust the height of the saddle, and enhancing the safety of the rider while riding the bicycle.