Visa to visit Andorra
You do not require a visa to enter the country and can remain for up to 90 days. Because you must first travel to France or Spain and cannot fly there immediately, you should only obtain a valid Schengen visa if necessary (depending on your nationality). If you are a citizen of a nation that is not a member of the EU but is a member of the Schengen region, you must have a valid passport in order to enter Andorra under the Andorra Visa Policy. If you are a citizen of a country that is not a member of the Schengen Area, you must have a valid passport and a Schengen Multiple-entry Visa to cross the border between Spain and France, which you must do to visit Andorra.
However, since Andorra can only be accessed by passing through France or Spain, you should follow the relevant regulations for France or Spain, depending on which country you're traveling through to reach Andorra. Keep in mind that the Schengen visa regulations may apply de facto upon arrival. There are no fixed-wing airports in Andorra, but there are commercial helicopter services at heliports at La Massana (Cam Heliport), Arinsal, and Escaldes-Engordany. Andorra is not part of the Schengen area. If entering Europe on a Schengen visa, make sure your visa entitles you to repeated visits to avoid being refused entry to Spain or France following a stay in Andorra.