Forum:Ritual beast ulti-gaiapelio

Ritual beast ulti-gaiapelio's effect "During either players turn when a spell/trap card, or monster effect is activated. You can banish 1 "ritual beast monster" card from your hand, negate the activation, and if you do, destroy it."

If my opponents monster can't be destroyed by card effect, can I still negate the the first half of his monster effect?