This is a 1976 Italian 2 Fogli poster (39" x 55") for Japanese Kaiju movie Godzilla vs. Megalon, released in Italy under the title Ai confini della realtà.

The poster uses the Italian title "Ai confini della realtà", which literally translates to "At the borders of reality" (a title shared with the Italian name for the series The Twilight Zone).
The robot featured prominently is Jet Jaguar, a size-shifting hero who assists Godzilla in the film.