To provide a weighing method which allows a high precision powder weighing at continuous supply of powder.

A hopper 2 which reserves powder is placed on a mount through multiple load cells 3 for load detection, and with the use of a rotary feeder 11 provided at the lower part of the hopper 2, the powder in the hopper 2 is fed out, and when the reserved amount of powder in the hopper 2 decreases, it is refilled into the hopper 2 through a refill opening 2a at the upper part of the hopper 2, through a belt conveyer 10. Each load cells 3 are, through an A/D converter 4, connected to a computer 5, and with the use of a measurement signal inputted from the load cell 3 to the computer 5, a fed-out speed of the powder is calculated and the fed-out speed is time-integrated, so that the weight of powder fed out in a specified period can be calculated. The hopper 2, the rotary feeder 11 and a cover 12 of the belt conveyer 10 are connected through bellows 20 and 21.