Investment deposit, is a kind of the deposits in interest-free banking system in Iran which had been faced the absence of law for a prolonged time. From 1362 (1983) interest-free banking law distributed deposit contracts to al-Qard al-Hasan and term deposits, there were no regulation for Investment deposit contracts except Mudarabah contract in civil law. Although further studies show that deposits were named as “advocacy” term (note of article 3 in the mentioned law); but this contract's description has not been covered by the regulation for advocacy law.

 This study tries to illustrate the legal essence of investment deposits. At first, the specification of investment deposits has been determined, afterward compared them with defined contracts. Finally, in addition to present the legal essence of investment deposits, it offers solutions to adapt these deposits with the current economic condition