Visitors to Indonesia must obtain a visa from one of the Indonesian diplomatic missions unless they come from one of the visa exempt countries or one of the countries eligible for visa on arrival. All visitors must hold a passport valid for 6 months.

Visa policy map

Passport must be valid for at least 6 months from the date of arrival and have valid return ticket. The immigration officer at the port of entry may ask the passenger to produce any necessary documents (such as hotel reservation and proof of finance). Prior to arrival, foreign passengers are normally given ‘arrival and departure’ cards and the ‘departure’ portion is necessary to be kept as it needs to be returned to the immigration officer upon leaving the country.

Visa Free

Tourists holding passport from the following 15 countries are eligible to enter and remain in Indonesia without a visa for 30 days.

Visa on Arrival (VOA)

Nationals of the following 62 countries may apply for a Visa on Arrival for a length of stay of 30 days by paying US$25 at major entry points.

 All European Union and EFTA member states EXCEPT  Croatia[show]

 All Cooperation Council for the Arab States of the Gulf member states[show]

also the citizens of countries listed below:

Visa before arrival

Nationals who are not eligible for visa free or VOA need to apply the visa at an Indonesian embassy or consulate.

Nationals of San Marino require visa at all times including for transit.^[6] Otherwise other nationalities can transit through Indonesian airports for up to 8 hours.

Source: http://en.wikipedia.org/wiki/Visa_policy_of_Indonesia
For more detail information, please visit: http://www.deplu.go.id/Pages/Default.aspx?l=en