To dry wood chips by using steam of a boiler device and minimizing its used steam amount, to secure a steam amount to be used as a primary heat source, to improve drying capacity even with use of a small steam amount, and to improve combustibility.

The boiler system includes a drying conveyance device 30 conveying wood chips W supplied a predetermined amount from a supply device 1 while drying, and the boiler device 60 burning the wood chips W from the drying conveyance device 30 and generating steam by heat exchange of combustion gas and water. The drying conveyance device 30 is composed by providing a cylindrical outer shell 33 forming a conveyance space E of the wood chips W by an inner side conveyor, a steam circulation space S is provided in the outer shell 33, a steam feeding pipe line 47 feeding one part of the steam generated by the boiler device 60 is arranged in the steam circulation space S, and an exhaust gas feeding pipe line 50 feeding one part of exhaust gas exhausted from the boiler device 60 is arranged in the conveyance space E of the outer shell 33.