Abstract: In the construction method of a multi floor building, non load bearing walls which are made from pre-cast concrete and are erected upon edge portions of the floor slabs, are formed of a height which is roughly equal to the height of each floor of the building. The non load bearing wall for an upper floor is elected upon the non lead bearing wall which has been erected upon the floor slab for a lower floor. A floor slab shuttering for the upper floor is built at the inner side of the non load bearing wall for the upper floor and at the partway in the vertical direction of the non load bearing wall for the upper floor, with the non load bearing wall forms a portion of the shuttering, and concrete is poured within this floor slab shuttering to construct the floor slab for the upper floor.