This paper proposes an estimating method of the pressure loss of self-compacting concrete passing through the gaps between reinforcing bars, and proposed two types of easy dynamic mechanism models, the theory of virtual minute tube model and friction between solid particles. Suitability of these models were investigated by several experiments accepted the theory of rheology. Results of these experiments, they were made known, pressure loss could be estimated suitably using unit absolute volume ratio of coarse aggregate and the gap size between reinforcing bars, and in the case of theory of virtual minute tube model, pressure loss could be estimated suitably using the yield stress of mortar, length and radius of virtual minute tube.