An operating system for estimating a task that an operator should perform according to a user's request by allowing the user who uses an in-vehicle device of the operating system and the operator, who operates an operator terminal of the operating system, to communicate with each other through a center of the operating system, the center comprising: a requested task estimation unit that estimates a candidate for a requested task from information included in an utterance of a first speaker, the first speaker being the user, wherein the requested task estimation unit extracts a plurality of words included in the utterance of the first speaker, reads an attribute associated with each of the words from a database in which one or a plurality of attributes are stored so as to be associated with each of the words, reads a domain of a candidate for the task associated with the attribute from a database in which one or a plurality of domains of a candidate for the task associated with the one or plural read attributes are stored, wherein the requested task estimation unit totals, for the domain read for each of the words, a score according to the degree of importance of the domain with respect to the word and estimates a candidate for the task related to a domain with the highest total score as a candidate for the requested task, the center further comprises an action task selection unit that selects the requested task from the candidate for the requested task, which has been estimated by the requested task estimation unit, on the basis of information included in an utterance of a second speaker, the second speaker being the operator, the action task selection unit extracts a plurality of words included in the utterance of the second speaker, reads an attribute associated with each of the words from a database in which one or a plurality of attributes are stored so as to be associated with each of the words, reads a domain of the task associated with the attribute from a database in which one or a plurality of domains of the task associated with the one or plural read attributes are stored, and totals, for the domain read for each of the words, a score according to the degree of importance of the domain with respect to the word and selects the task related to a domain with the highest total score as the requested task from the candidate for the requested task. a requested task estimation unit that estimates a candidate for a requested task from information included in an utterance of a first speaker, the first speaker being the user, wherein the requested task estimation unit extracts a plurality of words included in the utterance of the first speaker, reads an attribute associated with each of the words from a database in which one or a plurality of attributes are stored so as to be associated with each of the words, reads a domain of a candidate for the task associated with the attribute from a database in which one or a plurality of domains of a candidate for the task associated with the one or plural read attributes are stored, wherein the requested task estimation unit totals, for the domain read for each of the words, a score according to the degree of importance of the domain with respect to the word and estimates a candidate for the task related to a domain with the highest total score as a candidate for the requested task, the center further comprises an action task selection unit that selects the requested task from the candidate for the requested task, which has been estimated by the requested task estimation unit, on the basis of information included in an utterance of a second speaker, the second speaker being the operator, the action task selection unit extracts a plurality of words included in the utterance of the second speaker, reads an attribute associated with each of the words from a database in which one or a plurality of attributes are stored so as to be associated with each of the words, reads a domain of the task associated with the attribute from a database in which one or a plurality of domains of the task associated with the one or plural read attributes are stored, and totals, for the domain read for each of the words, a score according to the degree of importance of the domain with respect to the word and selects the task related to a domain with the highest total score as the requested task from the candidate for the requested task.