To provide both a floor mat for a barn having elasticity and water permeability, preventing infiltration into a floor face and aiming at an increase in milking amount and feed intake amount and health supervision and a method for constructing the same.

This mat comprises a mat upper layer part (1) having elasticity and water permeability obtained by piling and binding elastic small piece bodies and small particle bodies (4) and a waterproof layer part (2) laid under the whole or a part of the underside of the mat upper layer part. A mat lower layer part (3) may be piled and arranged so as to cover the whole underside part of the mat upper layer part with holding the waterproof layer between the layer parts. This method for constructing the floor mat comprises laying the waterproof layer part on the whole or a part of a fixed floor face (5) and constructing the mat upper layer part in a laminated state so as to include the waterproof layer part and to cover the whole of a fixed floor face. Otherwise, the mat lower layer part is laid on the fixed floor face, the waterproof layer part is applied to the whole or a part of the top of the mat lower layer part and the mat upper layer part is constructed in a laminated state so as to cover the whole top side of the mat lower layer part with holding the waterproof layer part between both the mat layer parts.