PURPOSE: A tunnel stay structure of a center floor is provided to prevent the reduction of aerodynamic performance and collision performance due to a tunnel stay in the bottom of an automobile body during driving. CONSTITUTION: A tunnel stay structure of a center floor is composed as follows. A center floor(10) is comprised in the bottom of an automobile body. A left side sill panel(21) and a right side sill panel(22) are comprised in the both sides of the center floor. A tunnel stay(100) connects the left side sill panel and a right side sill panel.
