A water-containing solid fuel drying apparatus for drying water-containing solid fuel injected into a drying vessel by heating the water-containing solid fuel, comprising: a dryer including the drying vessel and a heat transfer pipe through which a drying gas can flow and which is disposed in the drying vessel, wherein the drying vessel is arranged such that scavenging gas can be injected into the drying vessel; a dust collector arranged such that the scavenging gas that has flowed out of the drying vessel is introduced into the dust collector in a form of microparticle-containing mixed gaseous fluid that contains vapor evaporated from the water-containing solid fuel and microparticles of the water-containing solid fuel, for removing the microparticles from the microparticle-containing mixed gaseous fluid; a compressor for compressing vapor-containing mixed gaseous fluid introduced thereinto by the scavenging gas that has passed through the dust collector; a heat exchanger for preheating the vapor-containing mixed gaseous fluid that is to be introduced into the compressor from the dust collector with pressurized mixed-gaseous fluid that has been compressed at the compressor; and a gas-liquid separating device in which gas-liquid separation is performed on the pressurized mixed gaseous fluid supplied from the heat exchanger and employed as drying gas that radiates heat by passing through the heat transfer pipe by introducing water-containing scavenging gas which flows out from the heat transfer pipe and contains moisture formed through condensing of vapor contained in the gas, wherein the scavenging gas from which moisture has been removed at the gas-liquid separating device circulates through the water-containing solid fuel drying apparatus while undergoing repeated phase changes through the microparticle-containing mixed gaseous fluid, the mixed gaseous fluid, and the water-containing scavenging gas, in this order, and the water-containing solid fuel is dried by heating the water-containing solid fuel with latent heat of vapor contained in the pressurized mixed gaseous fluid and sensible heat of the pressurized mixed gaseous fluid. a dryer including the drying vessel and a heat transfer pipe through which a drying gas can flow and which is disposed in the drying vessel, wherein the drying vessel is arranged such that scavenging gas can be injected into the drying vessel; a dust collector arranged such that the scavenging gas that has flowed out of the drying vessel is introduced into the dust collector in a form of microparticle-containing mixed gaseous fluid that contains vapor evaporated from the water-containing solid fuel and microparticles of the water-containing solid fuel, for removing the microparticles from the microparticle-containing mixed gaseous fluid; a compressor for compressing vapor-containing mixed gaseous fluid introduced thereinto by the scavenging gas that has passed through the dust collector; a heat exchanger for preheating the vapor-containing mixed gaseous fluid that is to be introduced into the compressor from the dust collector with pressurized mixed-gaseous fluid that has been compressed at the compressor; and a gas-liquid separating device in which gas-liquid separation is performed on the pressurized mixed gaseous fluid supplied from the heat exchanger and employed as drying gas that radiates heat by passing through the heat transfer pipe by introducing water-containing scavenging gas which flows out from the heat transfer pipe and contains moisture formed through condensing of vapor contained in the gas, wherein the scavenging gas from which moisture has been removed at the gas-liquid separating device circulates through the water-containing solid fuel drying apparatus while undergoing repeated phase changes through the microparticle-containing mixed gaseous fluid, the mixed gaseous fluid, and the water-containing scavenging gas, in this order, and the water-containing solid fuel is dried by heating the water-containing solid fuel with latent heat of vapor contained in the pressurized mixed gaseous fluid and sensible heat of the pressurized mixed gaseous fluid.