Abbas Kadkodaye, a member of the Guardian Council, said on Tuesday the body had also speeded up work on re-examining the massive rejections.
There have been widespread allegations that hardliners in the country are seeking to rig the result of the 20 February parliamentary polls.
"After the order was given by the Supreme Leader (Ayat Allah Ali Khamenei), we have been obliged to speed up our work. So far 200 candidates have been approved," Kadkodaye said in a statement on the Guardian Council's website.
He did not identify the cases on which the body had reversed its decision.
Last week, Khamenei ordered the 12-member body, which screens all laws and candidates for public office and all of whose members he directly or indirectly appoints, to re-examine their blacklist and be less stringent.
Khamenei has asked the Guardian
Council to be less stringent
The electoral vetting arm of the Guardian Council, the Surveillance Commission, had disqualified 3605 of the 8157 people seeking to stand.
Most on the blacklist were reformers, among them some 83 incumbent MPs and some of the reform movement's most prominent figures.
According to Muhammad Jahromi, a spokesman of the Surveillance Commission, about 3100 appeals have been lodged from disgruntled contestants.
Many had had their candidatures rejected on the grounds they did not respect Islam.
On Monday, President Muhammad Khatami's political party, the Association of Combatant Clerics, threatened to boycott the election if the ban on reformist candidates was not overturned.
Khatami's party has threatened
to boycott the elections
On Sunday, 18 reformist parties in the 2nd of Khordad movement, named after the date in the Iranian calendar of Khatami's election in 1997, said in an open letter to the president they would decide on Thursday whether to boycott the election.
The coalition, led by the Islamic Iran Participation Front of Khatami's brother Muhammad Reza Khatami, said it would make its decision based on the extent of the Guardian Council's review process.
But the Guardian Council is not expected to complete its work by the end of the month, with a definitive list to be released around 10 February - just 10 days before the polls.
Reformists are complaining if a final list is only published a week or so before the elections, they will have little time to prepare a campaign.