A method of evaporation control of a sample which is stored in a thermally insulated state is configured for preventing evaporation or denaturing of the samples and specimens. The method includes carrying the samples contained in individual containers out from a cold container having a capability of cold storage. An elapsed time that each sample container has been removed from the cold container is measured and is compared with a preset time. If the elapsed time is less than the preset time, the sample container can be returned to the cold container. An alarm is output if the elapsed time exceeds the preset time.