Abstract: The present invention relates to a prefabricated modular building composed of a roof, a floor and vertical panels assembled together, said building further comprising four vertical corner elements placed respectively at the four corners of the building, extending over the whole height of the vertical panels and forming ties between the roof and the floor, and vertical securing members anchored, at one of their ends, in one of the horizontal elements (roof or floor), passing through each corner element and blocked, at their other ends, in the other horizontal element (floor or roof).