A memory controller schedules requests to memory devices according to scores. For this purpose, the memory controller variably adjusts weights for determining the scores with respect to the requests, calculates the scores using the weights, and determines a processing order of the requests according to the scores. The memory controller includes a request queue, a scheduler, and a weight generation circuit. The request queue stores the requests provided from an external device. The scheduler calculates a score for each request included in the request queue and determines the processing order of the requests based on the scores for the requests. The weight generation circuit generates a weight vector including the weights used to calculate the scores.