A computing device performs a continual learning method of learning a plurality of task in a sequential order. The computing device uses, in a forward pass of a neural network for learning a current task of the plurality of tasks, a plurality of weights including selected weights, the selected weights being selected in a previous task of the plurality of tasks, freezes the selected weights and updates weights excluding the selected weights from the plurality of weights in a backward pass of the neural network for learning the current task, obtains a binary mask for selecting some weights of the plurality of weights based on a weight score of each of the plurality of weights, and finds a subnetwork of the neural network for the current task based on the binary mask.