The investigation into Lee means all four living former South Korean presidents have been convicted, charged, or embroiled in criminal inquiries.
South Korea's former President Lee Myung-bak arrives at the prosecutors' office to be questioned over allegations that he took bribes when in office, in Seoul, South Korea March 14, 2018 in this still image taken from video.
Former South Korean President Lee Myung-bak on Wednesday appeared before state prosecutors for questioning over multiple corruption charges including bribery, embezzlement and tax evasion, local TV footage showed.
South Korean politicians under investigation often will apologize for causing trouble while still denying involvement.
He was to be interrogated by three prosecutors and Yonhap news agency said the questioning - which will be videotaped - was expected to last around 20 hours, with prosecutors having prepared around 120 pages of questions relating to some 20 alleged offences.
President Moon, Blue House aides and prosecutors have flatly rejected the claim. Lee was a conservative leader whose successor as president, Park Geun-hye, was removed from office previous year and is standing trial on bribery and other charges.
Their sentences were later commuted to life in prison, and they were eventually pardoned and released after serving about two years each.