A volume susceptibility (χs1) of a first dispersoid particle (s1) is obtained. A second dispersoid particle (s2) that is the first dispersoid particle (s1) to which an adsorbate is adsorbed is obtained. A volume susceptibility (χs2) of the second dispersoid particle (s2) is obtained. An amount of a functional group of the first dispersoid particle (s1) is analyzed through obtaining an amount of the adsorbate included in the second dispersoid particle (s2) based on the volume susceptibilities (χs1) and (χs2) of the first and second dispersoid particles (s1) and (s2).