A semiconductive GaAs wafer has a diameter of 4 inches or more, and an in-wafer plane dislocation density of 30,000/cm.sup.2 or more and 100,000/cm.sup.2 or less. A semiconductive GaAs wafer is made by growing a GaAs single crystal under a temperature gradient of 20.degree. C./cm or more and 150.degree. C./cm or less formed in the crystal so that the semiconductive GaAs wafer has an in-wafer plane dislocation density of 30,000/cm.sup.2 or more and 100,000/cm.sup.2 or less.