It is an object of the present invention to provide a conveyor which estimates weight of a transport object while it is carried without using devices such as a load cell which directly measures weight.The conveyor has a plurality of zones forming a series of carriage ways. An approach-run zone and a weight-measurement zone are arranged adjacently in the conveying direction and are provided with different drive motors. The drive motor of the approach-run zone and the drive motor of the weight-measurement zone are controlled with respectively different predetermined rotation speeds as their target rotation speeds. A rotation speed sensing means obtains the change of rotation speed of the drive motor in the weight-measurement zone when a transport object is conveyed into the weight-measurement zone from the approach-run zone, and a weight sensing means then calculates the weight of the transport object based on the change of the rotation speed.