1. A product search method in a product search system, the method comprising: maintaining and storing a database in a memory, the database including a plurality of product identifiers and a plurality of product categories associated with the respective product identifiers; maintaining a plurality of search logics associated with categorical types of products, at least one predetermined search logic being assigned to each categorical type of products, each of said plurality of search logics including a set of search steps wherein at least two categorical types of products are associated with at least two different search logics and said at least two different search logics include different sets of search steps; receiving a search request including an original query for search of a product from a user terminal; determining whether a product identifier corresponding to the original query exists; extracting a category query associated with the original query and selecting at least one said product category included in the database using the category query, when the product identifier corresponding to the original query does not exist; selecting at least one product category including the product identifier as a category corresponding to the received original query, when the product identifier corresponding to the original query exists; identifying a categorical type of product associated with the selected product category; determining a search logic corresponding to the categorical type of product from among the plurality of search logics; in response to the search request, performing a search of the database for products by applying said determined search logic corresponding to the identified categorical type of product such that different search logics are applied depending on the categorical type of product; and outputting a search result including the searched products, wherein, when the identified categorical type of product is a first categorical type of product, the predetermined search logic corresponding to the first categorical type of product performs search steps in a predetermined sequence until a number of the searched products included in the search result exceeds a predetermined value, said search steps being selected from the group comprising: a search step of generating a first query by removing a space, a special character or both from the original query and of searching the database for products using the first query; a search step of generating second queries by separating the original query into a plurality of words according to the space, each of the plurality of words being the second queries, and of searching the database for products by using one or more words among the second queries, each of said one or more words being a combination of at least two selected from the group consisting of English alphabetic characters, numerals, special characters; a search step of generating third queries by separating the original query into a plurality of words according to the space, each of the third queries having an initial letter of an English alphabetic character and at least one numeral, and of searching the database for products by using the third queries; and a search step of generating fourth queries by separating the original query into a plurality of tokens according to the space based on analyzing the morpheme of the original query, each of the tokens comprising either a group of only alphabetic characters or a group of only numerals, and of searching the database for products by using the fourth queries.