Abstract: In a construction method of boardlike building elements each having a groove formed in its upper edge face in the lengthwise direction thereof, the boardlike building elements are fixed to the wall surface of a building body in arranged form by fixing each first fixture to the building body such that the horizontal segment of each first fixture extends perpendicularly to the wall surface, inserting each second straight fixture in the downward direction in a slit which is formed in a distal edge portion of the horizontal segment of each first fixture in parallel to the wall surface, and fitting the lower edge of each second fixture in the upper edge groove of each boardlike building element, whereby the upper portion of each boardlike building element is fixed to the building body.