A method of testing semiconductor packages, which performs an electrical test on the semiconductor packages after receiving the semiconductor packages into insert pockets of a test tray and connecting with sockets of a tester by using pusher units each including a heater, includes receiving temperature information of the semiconductor packages from the tester while testing the semiconductor packages, calculating an overall average temperature of the semiconductor packages from the received temperature information, and individually controlling operations of heaters of the pusher units based on difference values between the overall average temperature and individual temperatures of the semiconductor packages.