1. A terminal for searching an image, comprising: a feature point extractor, executed by a processor, to extract at least one feature point from an input image; a descriptor generator, executed by the processor, to generate a feature point descriptor which is hierarchical by compressing the extracted at least one feature point, the feature point descriptor being information that describes the feature point through an orientation and a position of at least one grid cell located around the at least one feature point; and an information searcher, executed by the processor, to search for information matching the feature point descriptor from a database, wherein the descriptor generator calculates an error rate of the feature point descriptor, and determines whether to additionally describe the at least one grid cell located around the at least one feature point based on the error rate.