In the ordinary designing practice of wooden girder-bridges, paving planks are commonly assumed to be simple beams. However, in fact they act on as continuous beams, e. i. any applied load is transmitted by planks and borne by all girders. The author analysed the load-distrbution, and the proportions of distributed load borne by each girder are theoretically calculated. It is suggested by the numerical examples that, the load-transmitting effects of paving planks are considerably large, and therefore, they should be taken into account for the design of girder bridges.