What's it called?

Interesting question. I've only ever called it the "blender top" but I suppose I'd call it a pitcher, since it has a pour spout and a handle.

Thanks for your reply! I'll call it "blender top" from now on too.

I've looked for it on the internet and found "glass jar" at Walmart.

http://www.walmart.com/ip/Black-Decker-10-Speed-Blender-Red/15806198

Which word am I going to use now?

My dictionary says "jug" is used in British English, which is the same as "pitcher" in Ame

If I can still find my owner's manual I"ll see what they call it.

How about "blender jar"?

That's the word I found when I took a look at walmart.com.

http://www.walmart.com/ip/Black-Decker-10-Speed-Blender-Red/15806198

But I wasn't sure if this was used in USA.

It's not a commonly used term and I'm not sure there's a standard word for it - if I were you, I'd just go with something like "blender x" and not worry about it. Unless you choose a deliberately obscure word, people will know what you mean.

The fact that native speakers can't think of a suitable word suggests that we don't often feel the need to talk about this particular thing.

I"ve thought about this since it was first posted, and I think I just refer to it as "the blender." If I say "Okay, now put 1 cup of yogurt and 1 cup of milk in the blender" no one will think I mean the base where the motor is. If I say "Make sure you wash the blender out after you use it" no one will think I mean the electronic parts need a scrubbing.