1. A method for building a database for fingerprinting positioning, comprising: generating, by a database building device, raw data by collecting received signal strengths (RSSs) for access points (APs) at each sample point (SP); generating a cluster table by clustering SPs for each of the APs according to the RSS for the AP, using the generated raw data; and building, by the database building device, a radio map by deleting data of which RSS measurement rates are equal to or less than a predetermined reference value, from the generated raw data, wherein: the generating of the cluster table comprises: estimating, by the database building device, a signal attenuation rate per distance in a state where the SP having the maximum RSS is set to the start point; determining the number of clusters according to the estimated signal attenuation rate per distance; calculating the initial center value of a cluster based on a difference between the maximum value and the minimum value of the RSS and the number of clusters for an arbitrary AP; and calculating a final center value of the cluster for the arbitrary AP by performing an unsupervised learning algorithm using the calculated initial center value as a start value; in the generating of the raw data, the database building device generates the raw data by repetitively measuring the RSSs for the respective APs at each SP; and in the calculating of the initial center value based on the difference between the maximum value and the minimum value of the RSS and the number of clusters, the database building device calculates the center value of an m-th cluster by the following equation: R min + ( m - 1 2 ) × R max - R min CN , where R min represents the minimum value of the RSS, R max represents the maximum value of the RSS, and CN represents the number of clusters.