1. A robot which executes a task by making autonomous motions according to communication with a support server provided with a task database, comprising: a first processing element configured to recognize a content of a designated task among a plurality of tasks stored in the task database according to communication with the support server, to evaluate a cost indicating a labor or load required for a self robot to execute the designated task according to the recognized content, and to store the evaluated cost in the task database according to communication with the support server; and a second processing element configured to recognize whether the cost of the self robot stored in the task database according to communication with the support server is lowest in a robot group containing other robots, and to control the motions of the self robot so as to execute the designated task on a condition that the cost thereof has been recognized to be the lowest.