You may need a visa for Bulgaria depending whether your country is member of EU and the length of your stay in the country:
Up to 30 days – no visa is required for citizens of EU member-state;
Up to 90 days – you are required to get a visa type “С” from the Bulgarian embassy;
Up to 1 year – you are required to get a one-year visa type “D” from the Bulgarian embassy.
No visa is required for any citizen of EU member-state willing to purchase real estate in Bulgaria.
Foreign citizens are required to present the address that they shall stay in within 48 hours from arrival in front of competent authorities.
Foreigners with valid international passports who are citizens of EU member-states, Norway, Island, South Korea, Monaco, San Marino and Switzerland may stay up to 90 days in Bulgaria without a visa.
Citizens of Tunisia with valid international passports may stay in Bulgaria up to 60 days without a visa.
Foreign citizens who may stay in Bulgaria without a visa up to 30 days should be citizens of Australia, Andorra, Israel, Canada, Liechtenstein, Macedonia, New Zealand, USA, Serbia and Montenegro, Romania and Croatia.