A transactional agent is a mobile agent which manipulates objects distributed in computers. A transactional agent is composed of routing and manipulation subagent. A way to move to computers is decided in the routing agent. Objects in each computer are manipulated in a manipulation agent. After visiting computers, a routing agent makes a decision on commitment by using the commitment condition. In addition, objects obtained from a computer in the manipulation agent have to be delivered to other computers where the transactional agent is performed. A schedule to visit computers is made from the input-output relation of manipulation agents. We discuss a model of transactional agent and implementation of a transactional agent on database servers and evaluate the transactional agents. We evaluate the transactional agent model in terms of accessing time compared with the traditional client-server model.