A memory may include a plurality of word lines to which one or more memory cells are connected, and a control unit suitable for activating and precharging a first word line that is selected based on an address of a high-activated word line during a target refresh operation while sequentially activating and precharging the plurality of word lines in a refresh operation, wherein the control unit is suitable for writing a test data to one or more first memory cells connected to the first word line during the target refresh operation in a test mode, wherein the high-activated word line is a word line activated over a reference number or a reference frequency, among the plurality of word lines.