Paper physical property detecting device includes a first detector that measures a sheet of paper (hereinafter, merely referred to as a paper) made to stop temporarily on a conveyance path and acquires a first value corresponding to a first physical property, a second detector that measures a paper while conveying the paper on the conveyance path and acquires a second value corresponding to a second physical property with regard to a physical property different from the first physical property; and a corrector that corrects the first value on a basis of the second value and creates post correction data.