"In just over 50 days, we recorded no less that 115 executions, that is an average of more than two each day," Amnesty secretary general Irene Khan said in a statement.
"This represents a significant increase, even compared to the appallingly high rate of executions that has been so long a feature of the human rights scene in Iran."
The statement said between January 1 and the election on June 12, Amnesty recorded at least 196 executions, placing Iran second worldwide after China in the number of executions carried out.
"The 115 executions known to have been carried out since the presidential election on 12 June included 14 executions on 2 July, 20 on 4 July, 13 on 14 July and a further 24 executions on 5 August, the day of the inauguration," it said.
According to AFP's count based on news reports, at least 219 people were executed in the Islamic republic between January 1 and August 5.
"In recent weeks world attention has understandably been focused on the Tehran authorities? brutal attempts to suppress the mass and largely peaceful protests that followed the widely disputed official outcome of the presidential vote," Khan said.
"Yet, as these grotesque figures show, there has been no let up in other longstanding patterns of human rights abuse — in fact, the reverse."
About 30 people have been killed in the violence that erupted after the June 12 poll. Hundreds more have been wounded and around 110 are currently on trial.
The Amnesty statement said the group recognised the "that the true total number of executions is almost certainly higher even than the number it has been able to record."
It said most of those executed were said to have been convicted of drug smuggling or related offences.
In 2008, Iran executed 246 people, second only to China.
Tehran says the death penalty is a necessary tool for maintaining public security and is only applied after exhaustive judicial proceedings.
Murder, rape, armed robbery, drugs trafficking and adultery are all punishable by death in Iran.
