Surface analyzer of object to be measured and analyzing method

A method of analyzing a surface of a compound having an unknown composition ratio, comprising:

• a first step of finding a relation between a valence of a multicharged ions beam and respective counts of secondary ions generated from specific elements on a surface of a standard compound in response to irradiation of the multicharged ion beam thereonto, by radiating the multicharged ions beam to the standard compound at multiple times while changing the valence of the multicharged ions beam each time, the standard compound being constituted of same constituent elements as the compound to be measured and having a known stoichiometric composition ratio;
• a second step of finding a valence of the multicharged ions beam at which a count ratio of secondary ions from the specific elements is substantially equal to the stoichiometric composition ratio of the standard compound based on the relation between the valence of the multicharged ions beam and the respective counts of the secondary ions found in the first step;
• and
• a third step of performing surface analysis of the compound with the unknown composition ratio by radiating a multicharged ions beam having the valence found in the second step to the compound with the unknown composition ratio.