The weight of the postal matter which is conveyed in a standing condition, in order to accurately metered without increasing the size of the entire apparatus, a paper sheet weighing device serves to sandwich the paper sheet conveyed to the conveying path, comprising a first handling means for stopping the behavior of the paper sheets in a standing state at a predetermined position, and a metering means for metering the weight of the paper sheet stopped at the predetermined position, the first handling means, the paper sheets are weighed by the weighing means, sending to the outside from the predetermined position.