A device and method for classifying a category of data are provided. The device includes: a memory storing one or more instructions; and at least one processor configured to execute the one or more instructions stored in the memory to cause the processor to: identify a classification system of a category of data comprising a classification criterion of the category of the data and a plurality of keywords; obtain data comprising at least one sentence; and determine at least one category with respect to the at least one sentence of the data based on the classification system of the category of the data using a neural network that performs classification by unsupervised learning.