In a measuring device 50, a microwave receiving unit 52 is disposed behind a microwave transmitting unit 51 with respect to a powder object 2, and the microwave transmitting unit 51 and the microwave receiving unit 52 are each enclosed by a waveguide box. A waveguide box 6 for the transmitting unit is smaller than a waveguide box 8 for the receiving unit, and is enclosed by the waveguide box 8 for the receiving unit. An opening portion 7 of the waveguide box 6 and an opening portion 9 of the waveguide box 8 are mounted on a flat window material 5, and are aligned. The window material 5 is in contact with the powder object 2. Microwaves 3 transmitted from the microwave transmitting unit 51 are reflected by the powder object 2, are received, as scattered microwaves 4, by the microwave receiving unit 52, and are measured.