Speaking to reporters in the Austrian capital of Vienna, Amano said Head of the Atomic Energy Organization of Iran (AEOI) Ali Akbar Salehi has signed the roadmap on behalf of the country.
According to Amano, the roadmap calls for the IAEA, with Iran's cooperation, to make an assessment of issues relating to possible military dimensions (PMD) of the Islamic Republic's nuclear energy program by the end of 2015.
"This is a significant step forward toward clarifying outstanding issues regarding Iran's nuclear program," Amano added.
His remarks came as Iran and the Group 5+1 (Russia, China, the US, Britain, France and Germany) concluded more than two weeks of talks over Tehran's nuclear program in Vienna on Tuesday, in what a senior Iranian lawmaker explained as "successful".
The negotiating parties earlier today reached a conclusion over the text of a comprehensive deal on Tehran's nuclear program after 22 months of diplomatic negotiations.
Iranian Foreign Minister Mohammad Javad Zarif and the European Union Foreign Policy Chief Federica Mogherini, who has been coordinating diplomacy with Iran on behalf of the six powers, are going to hold a joint press conference to read a statement on the results of the marathon talks.