Citizens of the following countries do not need a visa, the entry period is normally for a maximum of six months:
Andorra, Anguilla, Antigua and Barbuda, Australia, Austria, Bahamas, Barbados, Belgium, Bermuda, British Virgin Islands, Brunei, Cayman Islands, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Falkland Islands, Finland, France, Germany, Gibraltar, Greece, Holy See, Hong Kong (BN(O) Passport or SAR Passport), Hungary, Iceland, Ireland, Israel (National Passport holders only), Italy, Japan, Latvia, Lithuania (biometric passports only), Liechtenstein, Luxembourg, Malta, Monaco, Montserrat, Netherlands, New Zealand, Norway, Papua New Guinea, Pitcairn Islands, Poland (biometric passports only), Portugal, Saint Kitts and Nevis, Samoa, San Marino, Singapore, Slovakia, Solomon Islands, South Korea, Spain, St. Helena, Sweden, Slovenia, Switzerland, Taiwan (must be ordinary passport including personal identification number), Turks and Caicos Islands, United Kingdom (including British (Overseas) Citizens who are re-admissible to the UK and British subjects with the right of abode in the UK) and United States(include US Green Card or permanent residence in the US) .
Obtaining a visa
All others will be required to obtain a Temporary Resident Visa to enter the country. Applicants are required to submit, as part of their application:
A valid travel document (such as a passport)
Two properly-formatted, passport-sized photos for all applicants
The application fee (The fee per person is $75 for a single entry visa, $150 for a multiple entry visa or $400 for a family (multiple or single entry)
Reservation confirmation (for tourists) or letter of invitation (for everybody else).
Proof that you have enough money for your visit to Canada. The amount of money may vary, depending on the circumstances for your visit, how long you will stay and whether you will stay in a hotel, or with friends or relatives.
Other documents as required. These documents could be identification cards, proof of employment, or a proposed itinerary.
If you plan to visit the United States and do not travel outside the borders of the US, you can use your single entry visa to re-enter as long as the visa has not passed its expiry date.
visa office: http://www.cic.gc.ca/english/visit/index.asp