From a series of kits produced by Imai called Megaro Zamac. I don't think there was ever an anime show related to this series, I think Imai simply produced them to cash in on the giant robot model craze. This particular mecha was obviously more than slightly inspired by the Imperial AT-AT from The Empire Strikes Back, though from the scale of the kit the real thing would be considerably more than twice the size of the AT-AT.
This is my second image featuring the Dha Gards model, this one was rendered in Cinema4D R8. The background was rendered in Vue 5 Infinite.