An evaluation device that works out an objective evaluation value of a degree of concentration is provided. The evaluation device includes an acquirer, a storage, a processor and a corrector. The acquirer is configured to acquire a processing time measured for each of tasks performed by a user. The storage is configured to store the processing time for each of the tasks. The corrector is configured to, based on load factors that are set in accordance with respective degrees of difficulty of the tasks, correct and change the processing times stored in the storage to respective effective times corresponding to a prescribed degree of difficulty. The processor is configured to work out an evaluation value of user's degree of concentration based on a statistic acquired from a collection of the effective times.
