Provided is a partial pressure measuring method and a partial pressure measuring apparatus by which a partial pressure distribution is easily measured in a vacuum chamber. The partial pressure measuring method and the partial pressure measuring apparatus includes: moving a local plasma source dedicated to partial pressure measuring provided in the vacuum chamber, to a location at which the measuring is to be performed; and measuring a partial pressure distribution in the vacuum chamber, by receiving emission of plasma generated by the local plasma source through a window which is formed in a wall part of the vacuum chamber and through which the emission passes, and thereby performing emission spectral analysis on intensity of the emission.