The invention provides a rotatable connector which can improve efficiency of a lead block assembling operation and a rotatable connector assembling method. The rotatable connector is provided with the components of a fixed-side housing; a movable-side housing which is connected with the fixed-side housing and furthermore can rotate relative to the fixed-side housing; a flat cable which winds an annular space between the fixed-side housing and the movable-side housing; and the lead block which is connected with end of the flat cable in a length direction and comprises a lead block assembly part that is kept to at least one selected from the fixed-side housing and the movable-side housing. The rotatable connector is characterized in that the lead block assembling part forms an accommodating space for accommodating the lead block; and furthermore the rotatable connector is provided with an opening which is used for being inserted into the lead block from the annular space side.