A plate-type heat transport device and electronic instrument are provided. The plate-type heat transport device includes a heat absorbing plane absorbing heat because of the evaporation of a working fluid, a heat emission plane opposing the heat absorbing plane and emitting heat because of the condensation of the working fluid, and a flow path two-dimensionally arranged between the heat absorbing plane and the heat emission plane to align with the heat absorbing plane and the heat emission plane, the flow path allowing the working fluid to flow therethrough for changing the phase of the working fluid, and the flow path being capable of two-dimensionally diffusing the working fluid by generating a capillary force in the condensed working fluid.