A test handler and method for operating a test handler for testing semiconductor devices are provided. The test handler includes a test tray located on one side of an opening apparatus in which a plurality of inserts are arrayed, wherein each insert comprises at least one semiconductor device loaded thereon, at least one opening unit for opening inserts at one part of the one side of the test tray, and a position changing apparatus comprises a motor including a driving pulley for moving at least one opening unit along a contact surface of the test tray such that the at least one opening unit changes positions on the test tray and is located at another part of the one side of the test tray in order to open inserts at the other part of the one side of the test tray.