The Principality of Andorra does not require any type of visa.
The Principality of Andorra is not a member of the Schengen Area. Access to the Principality is made through France or Spain. Thus, any national from a third-country travelling to Andorra must get information from the French or Spanish Embassies or Consulates (depending on the country of entrance) about the need of a Schengen visa, and when deemed necessary, about the visa obtaining procedures.
When the Schengen visa is required, third-country nationals shall apply for a double-entry or a multiple entry Schengen visa depending on how many times you will enter the Schengen area from Andorra.