A method for determining an acceptance/rejection of fine diameter wire bonding on a basis of a bonding area of a bonding portion of a fine diameter wire, comprising: heating the fine diameter wire with a laser device of a fine spot diameter; performing a temperature change measurement with a correction of an emissivity on a basis of a minute amount of infrared rays radiated from a heated portion of the bonding portion of the fine diameter wire, using a two-wavelength infrared radiation thermometer for performing temperature measurement with a correction of an emissivity; correcting a result of the temperature change measurement for absorptivity of said laser to determine a corrected temperature change measurement; and determining an acceptance/rejection of bonding by comparing and contrasting, on the basis of the corrected temperature change measurement, the corrected temperature change measurement, with a temperature change indicated by an acceptable product as a comparison criterion, wherein the temperature change measurement is for measuring the temperature change until a saturation temperature at which no temperature change is observable; wherein the step of correcting is for correcting the temperature change measurement to a temperature change measurement that would be given in a case where a reference heating power that is applied to an acceptable product as a comparison criterion in order to store a temperature change indicated by the acceptable product in a memory is set, and the same power has been absorbed by the bonding portion of an object to be measured; and wherein determining the acceptance/rejection is performed by comparing and contrasting the corrected temperature change measurement with a temperature change indicated by an acceptable product as a comparison criterion that has been corrected to the temperature change with the reference heating power. heating the fine diameter wire with a laser device of a fine spot diameter; performing a temperature change measurement with a correction of an emissivity on a basis of a minute amount of infrared rays radiated from a heated portion of the bonding portion of the fine diameter wire, using a two-wavelength infrared radiation thermometer for performing temperature measurement with a correction of an emissivity; correcting a result of the temperature change measurement for absorptivity of said laser to determine a corrected temperature change measurement; and determining an acceptance/rejection of bonding by comparing and contrasting, on the basis of the corrected temperature change measurement, the corrected temperature change measurement, with a temperature change indicated by an acceptable product as a comparison criterion, wherein the temperature change measurement is for measuring the temperature change until a saturation temperature at which no temperature change is observable; wherein the step of correcting is for correcting the temperature change measurement to a temperature change measurement that would be given in a case where a reference heating power that is applied to an acceptable product as a comparison criterion in order to store a temperature change indicated by the acceptable product in a memory is set, and the same power has been absorbed by the bonding portion of an object to be measured; and wherein determining the acceptance/rejection is performed by comparing and contrasting the corrected temperature change measurement with a temperature change indicated by an acceptable product as a comparison criterion that has been corrected to the temperature change with the reference heating power. <EOS>