I have U.S."green card" and I wish to visit Canada,next week.Do I need get Canadian visa for this trip?

No Visa.....read below as it is quoted from the Citizenship and Immigration Canada website.

If you plan to visit Canada, you must:

Have a valid travel document, such as a passport;

Be in good health;

Have enough money for your stay. The amount of money you will need can vary with the circumstances of the visit, how long you will stay and whether you will stay in a hotel or with friends or relatives. For more information, ask the Canadian visa office in your country or region.

Convince an immigration officer that you have ties, such as a job, home and family, that will take you back to your country of origin;

Convince an immigration officer that you will leave Canada at the end of your visit.

Many people do not require a visa to visit Canada. These include:

persons lawfully admitted to the United States for permanent residence who are in possession of their alien registration card (Green card) or can provide other evidence of permanent residence.

Until we annex Canada, you probably have to have whatever documentation they require. I do not know if a green card satisfies that requirement. But chances are, if you are calling it a "green card," you probably dont have one.

EDIT: All edits are after Asker's uncalled for additional comment.

EDIT: Hey asker, I was pointing out that someone who HAS one wouldnt put it in "quotations." I said I dont know if a green card satisfies the border agents from Canada. It was a legitimate comment. Maybe it's your QUESTIONS that should be avoided instead of my answers.

EDIT: LOL!!! I mean seriously asker. I just read some of your questions, and now fully understand the venom in your comment! That's just WAY too funny!

Depends on your passport. A green card doesn't mean that you are a citizen. If your country (passport) is from a country that requires a visa in order for you to visit Canada, then yes.

You need a passport.