Provided is a material selecting method used upon purifying an iridium complex by sublimation which includes: selecting an iridium complex having a specific structure and having a rate of weight loss of 45% or greater when heated to 500° C. at a heating rate of 2° C./min under the degree of vacuum of from 1×10−3 Pa to 1×10−1 Pa; and carrying out sublimation purification.