A robot and the like capable of executing a task in an appropriate condition from the viewpoint of execution economy even when a state of the task is altered. A cost is evaluated that represents a load or labor required for a robot (1) to execute a new task, and the cost information indicating the cost is transmitted to a support server (200) (bid procedure). The support server (200) designates the robot (1) having the lowest cost as a designated robot (1) and transmits an execution instruction for executing the new task to the designated robot (1). The robot (1) executes the task according to the execution instruction (contract procedure). By employing the task bid and contract system, a designated task is executed by an adequate robot (R) among a plurality of robots (R) in consideration of the execution economy of the designated task.