According to an aspect of an embodiment, a method for a text classification using multi-task learning executed by a server, the method includes: a step of generating text classification learning data by executing a pre-processing process on raw data collected through a network; a step of learning a category classification in a first classification system preset through a first text classification model using the text classification learning data as an input; a step of learning a category classification in a second classification system preset through a second text classification model using the text classification learning data as an input; and a step of classifying the category in the second classification system by inputting text data received from a user terminal into the second text classification model.