1. A method of recommending a dialogue sticker by use of a server that is connected to a first user terminal and a second user terminal through a network and relays an utterance inputted to a messenger between the first user terminal and the second user terminal, the utterance including at least one of a text and an image, the method comprising: analyzing a dialogue situation from utterances between the first user terminal and the second user terminal; selecting a sticker candidate group by retrieving a dialogue situation similar to the analyzed dialogue situation from utterance data; calculating, based on preference information, an expression suitability for each sticker of the selected sticker candidate group; ranking the stickers in the sticker candidate group based on the expression suitability; and recommending a highest ranked sticker on a display device of the first user terminal, wherein the step of calculating an expression suitability comprises calculating a distance between an expression preference vector of a first user of the first user terminal and an expression vector for each sticker of the selected sticker candidate group and wherein the expression vector for a sticker has multiple elements and each element of the expression vector has a value that indicates the first user's preference on the sticker in association with a type of expression.