How to Change Opacity of Rubber Tool in Illustrator

It's the Eraser, Doug. They call it a "rubber" in some parts of the world.

What is the rubber tool anyway?

H-Drogo  wrote I wanted to lower down the opacity of rubber tool like that in Photoshop. But I couldn't in illustrator... Please, someone, tell me how to change the opacity of rubber tool in illustrator.

As Monika already stated:

You can't.

When working with vector graphics, it's best to shift your thinking away from image editing techniques. It's likely there are several ways to achieve the appearance you want, so if you can explain and/or show it in more detail, you'll get help with it here.

Screen shot needed.

Could you elaborate, maybe post a screenshot or mock-up to illustrate what you are trying to achieve?