A semiconductor memory device includes a row hammer management circuit and a refresh control circuit. The row hammer management circuit counts the number of times of access on each memory cell row to store the counted values in count cells of each memory cell row as count data. A hammer address queue in the row hammer management circuit stores candidate hammer addresses, which are intensively accessed, in response to a number of the candidate hammer addresses reaching a second number, transitions a logic level of an error signal provided to the memory controller, and, in response to the number of the candidate hammer addresses reaching the first number, outputs one of the candidate hammer addresses as a hammer address. The refresh control circuit performs a hammer refresh operation on victim memory cell rows which are physically adjacent to a memory cell row corresponding to the hammer address.