A roof structure includes a roof panel constituting a roof of a vehicle, a roof headlining constituting a ceiling of a vehicle cabin, and a stiffening board disposed between the roof panel and the roof headlining. The stiffening board is attached to a lower face of the roof panel by adhering at plural adhesion portions. Steps are formed at the stiffening board between the respective plural adhesion portions so as to widen a space between the stiffening board and the lower face of the roof panel.