An object of the present invention is to allow execution of a target function by an operation means that is easy to operate for a user. In order to achieve the object, a user interface system according to the present invention includes a function-means storage section 5 that stores candidates for a plurality of functions and candidates for a plurality of operation means for issuing an instruction to execute each function, an estimation section 3 that estimates a function intended by a user, and the operation means for issuing the instruction to execute the function, from among the candidates stored in the function-means storage section 5, based on information related to a current situation, and a presentation section 6 that presents the candidate for the function estimated by the estimation section 3, together with the candidate for the operation means for executing the function.
