To provide a method of detecting a size of a droplet hitting point which enables correct and simple calculation.

The method includes the step of forming a droplet hitting line, the step of detecting a width of the droplet hitting line, the step of reading a calculation condition, and the calculation step. In the step of forming the droplet hitting line, ink liquid droplets are continuously ejected from an ejecting part, the droplet hitting point is formed by adjacently hitting the ink liquid droplets to a position in contact with a droplet hitting point formed by ink liquid droplets ejected from the same ejecting part, and the droplet hitting line is formed by connecting the droplet hitting points formed by one ejecting part. The droplet hitting line formed on a medium to be recorded is read, and a width of the droplet hitting line is detected from the read image in the detecting step. A relationship between widths of droplet hitting lines and sizes of droplet hitting points conformed with a preliminarily prepared formation condition are read out on the basis of the formation condition of the droplet hitting line in the reading step. On the basis of the read relationship between widths of droplet hitting lines and sizes of droplet hitting points, the size of the droplet hitting point is calculated from the detected width of the droplet hitting line in the calculation step.