Provided is a method of searching for optimal neural network architecture based on channel concatenation. The method includes adjusting spatial size information of an input feature map candidate group so that the spatial size information of the input feature map candidate group corresponds to spatial size information of an output feature map, performing a channel-based concatenation operation on the input feature map candidate group, and additionally extending an output feature map that is the results of the channel-concatenated operation to the input feature map candidate group.