The gravitational interaction of antimatter with matter or antimatter has not been conclusively observed by physicists. ... Most methods for the creation of antimatter (specifically
Can antigravity be created?
Many people seem to think NASA has secret training rooms in which gravity can be turned off. Aside from the long-running Anti Gravity column in Scientific American, however, there is no such thing as antigravity.
Could antimatter fall up?
But in these theories, antimatter always falls slightly faster than matter; antimatter never falls up. This is because the only force that would treat matter and antimatter differently would be a vector force (mediated by the hypothetical gravivector boson).