To provide a roof structure which facilitates construction for greening a square corrugated roof, and allows a connector installed on a purlin to bear a panel load, attaining the greening of the square corrugated roof reduced in weight and not having a very high load strength.

The purlin 3 is installed on a beam 2 at desired intervals, a square corrugated plate 4 is placed on the purlin, the square corrugated plate is fixed to the purlin with the connector 11 from above the valley of the square corrugated plate, and a greening panel 6 having the panel 7 and a vegetation mat 8 integrated is placed on the connector so that the surface on the panel side faces the square corrugated plate, thereby fixing the greening panel to the connector so as to allow the connector to bear the load of the greening panel.