In this paper, a modified ant colony system (ACS) algorithm is proposed to find a shortest path based on the preference of links. Most of the shortest path search algorithms aim at finding the distance or time shortest paths. However, these shortest paths are not surely an optimum path for the drivers who prefer choosing a less short, but more reliable or flexible path. For this reason, we propose the preference-based shortest path search algorithm which uses the properties of the links of the map. The properties of the links are specified by a set of data provided by the user of the car navigation system. The proposed algorithm was implemented in C and experiments were performed upon the map that includes 64 nodes with 118 links.