Michael Bay's Home For Sale -- Optimus PRIME Real Estate

Michael Bay's Santa Barbara home doesn't transform into a robot, or attack aliens ... but you'll still need a blockbuster budget to buy it -- TMZ has learned the director is selling his picturesque pad for a WHOPPING $6.8 MILLION.

The sick pad -- featured on Realtor.com -- boasts 5,400 square feet, on 1.3 acres of property -- and has 3 bedrooms, 3 full baths and two half baths, a guest house, a gorgeous infinity pool ... and STUNNING views.

On top of all the features -- the house was designed by an award-winning Santa Barbara architect.