A sampling circuit may include a first timing determination circuit, a second timing determination circuit, and a sampling data output circuit. The first timing determination circuit may determine a first timing of sampling data in response to a first sampling timing signal. The second timing determination circuit may determine a second timing of the sampling data in response to a second sampling timing signal. The sampling data output circuit may output the sampling data having effective data values of the data between the first timing and the second timing in response to outputs from the first and second timing determination circuits.