1. A speech input system comprising: a speech input terminal provided with a speech input/output mean, a Web browser, and a display mean for displaying an access status to an external system and a search result; a speech portal server provided with a speech recognizing mean for receiving a speech from said speech input terminal to recognize it as a text, a command converting mean for checking the recognized text with a command text dictionary, and separating it into a command text and an object text, and a conversation control mean; and the application service provider which is provided with an information search mean for searching information based on the command text and the object text received from said speech portal server, and serves said speech portal server with a search result. wherein said conversation control mean has access to, and receives a service from said application service provider which provides different information based on the separated command text and object text, and provides said speech input terminal with the service.