A system for providing a query processing service based on personal-information protection, the system comprising: a client terminal configured to allow a user to input and send query content for solving a problem; a relaying and processing server configured to extract and process personal information contained in the query content received from the client terminal, transmit processed query content comprising the processed personal information to a cloud service server, and transmit an answer to a query received from the cloud service server to the client terminal; and the cloud service server configured to generate the answer to the query by analyzing the processed query content received from the relaying and processing server, and transmit the answer to the query to the relaying and processing server, wherein the relaying and processing server comprises: a personal-information extractor configured to extract common personal-information identification data having a common characteristic pattern and individual personal-information identification data having an individual characteristic pattern from the query content; and a relaying processor configured to process the common personal-information identification data and the individual personal-information identification data extracted by the personal-information extractor, and transmit the processed query content comprising the processed data, wherein the relaying and processing server further comprises a post verifier configured to extract additional personal-information identification data having a modified characteristic pattern from the query content after transmitting the answer to the query to the client terminal, wherein the modified characteristic pattern is a pattern in which spelling, orthography, or word spacing is not correct as compared to those of the common and individual characteristic patterns, and wherein the modified characteristic pattern is stored and managed in a relay storage, and continuously updated. a client terminal configured to allow a user to input and send query content for solving a problem; a relaying and processing server configured to extract and process personal information contained in the query content received from the client terminal, transmit processed query content comprising the processed personal information to a cloud service server, and transmit an answer to a query received from the cloud service server to the client terminal; and the cloud service server configured to generate the answer to the query by analyzing the processed query content received from the relaying and processing server, and transmit the answer to the query to the relaying and processing server, wherein the relaying and processing server comprises: a personal-information extractor configured to extract common personal-information identification data having a common characteristic pattern and individual personal-information identification data having an individual characteristic pattern from the query content; and a relaying processor configured to process the common personal-information identification data and the individual personal-information identification data extracted by the personal-information extractor, and transmit the processed query content comprising the processed data, wherein the relaying and processing server further comprises a post verifier configured to extract additional personal-information identification data having a modified characteristic pattern from the query content after transmitting the answer to the query to the client terminal, wherein the modified characteristic pattern is a pattern in which spelling, orthography, or word spacing is not correct as compared to those of the common and individual characteristic patterns, and wherein the modified characteristic pattern is stored and managed in a relay storage, and continuously updated. a personal-information extractor configured to extract common personal-information identification data having a common characteristic pattern and individual personal-information identification data having an individual characteristic pattern from the query content; and a relaying processor configured to process the common personal-information identification data and the individual personal-information identification data extracted by the personal-information extractor, and transmit the processed query content comprising the processed data, wherein the relaying and processing server further comprises a post verifier configured to extract additional personal-information identification data having a modified characteristic pattern from the query content after transmitting the answer to the query to the client terminal, wherein the modified characteristic pattern is a pattern in which spelling, orthography, or word spacing is not correct as compared to those of the common and individual characteristic patterns, and wherein the modified characteristic pattern is stored and managed in a relay storage, and continuously updated.