This paper proposes a new synchronous rectifier (SR) control scheme for high efficiency and density interleaved boost converter with a passive soft-switching cell (IBC-PSC). In the interleaved converters, the soft-switching cells including active components have been proposed to reduce the increase of switching losses proportionally to the number of modules. In this case, since the auxiliary current for soft-switching conditions is directly controlled by the active components, there are no additional conduction losses. However, these active components increase the weakness of the converter as well as the entire cost. In this paper, a new SR control scheme for IBC-PSC is proposed to achieve zero-voltage switching (ZVS) over a wide load range. Since the proposed scheme controls the auxiliary current without any additional active components, the conduction losses of IBC-PSC are reduced with high reliability and low cost. In addition, the proposed scheme enables the high power density design because the input current ripples are reduced as the load decreases. The experiment results from IBC-PSC verify the proposed control scheme.