A semiconductor device test handler for maintaining stable temperature in a test environment may include a loading unit that loads a plurality of semiconductor devices mounted on a test tray; a soak chamber configured to receive the test tray from the loading unit and to age the semiconductor devices at an aging temperature; and a test chamber configured to receive and test the aged semiconductor devices. The test chamber may include: a test board; a first chamber; a second chamber; one or more pipelines connected to the first and second chambers that allow a temperature-control medium to flow between the first and second chambers; a de-soak chamber that further ages the tested semiconductor devices so that the tested semiconductor devices substantially return to ambient temperature; and a sorting and unloading unit that sorts the tested semiconductor devices according to results of the test and that unloads the sorted semiconductor devices.