To eliminate risk of causing rain leakage, when rainwater overflows and flows in clearance between roof tiles, since a rainwater flow passage of an inserting part is narrowed by forming a receiving part, in a flat roof tile for preventing floating of the roof tile by blow-in of a strong wind by laying the roof tile so as to cover the receiving part with an engaging part when laying the roof tile, by forming the receiving part lockable with the engaging part in an inserting part having a water receiver, by projectingly forming the hook-shaped engaging part on the roof tile tail side.

The supporting part 13 forming a lower stage than the inserting part 12 is formed on a roof tile head of the inserting part 12. The hook-shaped engaging part 14 is formed inside a flashing 15 of a roof tile tail. When laying the roof tile 11, the floating of the roof tile 11 of a lower stage in a strong wind, is prevented by putting the engaging part 14 of the roof tile 11 of the lower stage on the supporting part 13.