To provide a connecting structure wherein wood is more firmly connected in a wooden building.

This connecting structure is used for connecting both the pieces of wood together by inserting a connecting area part of a connecting fitting (12) into the slit (41) of the wood, and making a fixing implement (43), composed of a pin, pass through a shaft hole and a fixing hole in a state wherein the shaft hole (42), formed in such a manner as to pass through the wood while crossing the slit, communicates with the fixing hole (36) formed in the connecting area part of the connecting fitting in such a manner as to correspond to the shaft hole. In the plurality of shaft holes (42a) and (42b), distances from an end surface of the wood are set as distances (L4) and (L3). In the plurality of fixing holes (36a) and (36b), distances from a reference position of the connecting fitting (12) are set as distances (L2) and (L1). The plurality of the shaft holes (42a) and (42b) are formed so that dimensions (L4-L3) of intervals among the plurality of shaft holes (42a) and (42b) can be different from dimensions (L2-L1) of intervals among the plurality of fixing holes (36a) and (36b), and forces (F1) and (F2) in directions opposite to each other act on the shaft holes (42a) and (42b) in a state wherein the fixing implement is inserted into the shaft hole and the fixing hole.