To provide a reinforcement structure of an automobile pillar which can increase rigidity of whole pillars with effective weight investment.

The load to be added to a center pillar 1 is transmitted to an opposite carbody side through side sill 5 on the lower side and roof 7 on the upper side in the center pillar 1 combining the roof 7 and the side sill 5 vertically, in order to form a continuing truss structure vertically including side sill 5 or a part equivalent to the side sill 5. This action has not only an effect to suppress the deformed velocity of the center pillar 1 to the inside of the car but also the effect to control the deformation mode from the local deformation to the whole deformation.