The present invention provides a self-refresh period adaptable for testing cells that are weak against hot temperature stress. An apparatus for controlling a self-refresh operation in a semiconductor memory device includes a first period selector for generating one of a period-fixed pulse signal having a constant period and a period-variable pulse signal having a variable period based on a temperature of the semiconductor memory device in a test mode; and a self-refresh block for performing the self-refresh operation in response to an output of the first period selector.