The present invention relates to a hearing aid fitting device, and an objective thereof is to improve usability thereof. To achieve this object, the fitting device (1) of the present invention comprises a hierarchical classification database (12) and an adjustment data determination component (20). A plurality of pieces of adjustment difference data obtained by the fitting of a hearing aid is hierarchically classified according to similarity in the amount of adjustment and is saved in the hierarchical classification database (12). The adjustment data determination component (20) determines fine adjustment data for the hearing aid by selecting a cluster from among a plurality of clusters in each hierarchical layer.