1. A particulate determination method for determining independence of a particulate as a measurement target based on a specific flag array that appears when a memory expressing a distribution of a judgment result of a signal pattern is scanned at a predetermined scanning range, wherein the shape of said signal pattern is an S shaped curve having a maximum value and a minimum value according to the size of the measurement target, and a predetermined recognition condition based on the shape of said signal pattern is a condition that a distance from a change start position to a change end position of the S shaped curve in the track direction is larger than a predetermined value, said method including: a data storage step of storing in a memory a flag that is obtained when the judgment result according to said recognition condition is true, and a flag that is obtained when the judgment result is false, into a memory; a particulate existence judging step comprising detecting said signal pattern based on respective difference recognition conditions and judging whether the particulate as the measurement target is present or absent from the existence of said signal pattern, and a particulate independency determining step comprising scanning the flag array stored in the memory using a scanning window having a predetermined size, determining whether the judgment result is true or false based on said recognition condition, calculating with a processor the number of the particulate as the measurement target from the flag array when the judgment result in the scanning window is true and judging independence of the particulate based thereon.