This invention is related to a powder of a tungsten alloy with a transition metal dissolved therein as a solid solution that is suitable as material for a cemented carbide represented by formula [1] and a material for a catalyst. The powder of tungsten alloy is characterized in that at least one transition metal element selected from the group consisting of cobalt, iron, manganese and nickel is dissolved as a solid solution in a tungsten grating and a peak derived from a bcc tungsten phase appears in an X-ray diffraction diagram. Formula [1]: M−W wherein M represents one or more elements selected from Co, Fe, Mn and Ni. The use of tungsten alloy powder can provide a tungsten carbide with a transition metal dissolved therein as a solid solution in which a solid solution phase comprising at least one transition metal element selected from the group consisting of cobalt, iron, manganese and nickel, tungsten and carbon is included in a tungsten carbide skeleton, and a tungsten carbide diffused cemented carbide.