Visa is not necessary for a stay inferior to three months( in a period of six) for those people from the following countries:

Andorra, Argentina, Australia, Austria
Bolivia, Brazil, Brunei, Bulgaria
Canada, Chile, Cyprus, Costa Rica, Croatia, Czech Republic
El Salvador, Estonia
Guatemala
Honduras, Hungary
Iceland, Israel
Japan
Latvia, Liechtenstein, Lithuania
Malaysia, Malta, Mexico, Monaco
Nicaragua, Norway, New Zealand
Panama, Paraguay, Poland
Korea
Romania
San Marino,Slovakia, Slovenia
The USA, The Vatican
Singapore, Switzerland
Uruguay
Venezuela
The People's Chinese Republic of Hong Kong and Macao( special administrative areas)
European Union (all members).

People from those countries that are not in this list should request a visa in the correspondent Embassy or Consulate. Both the request and pick up of the visa should be made personally, although in some cases they could designate a representative.

List of Embassies and Consulates of Spain all over the world: clic here