A new logic-based mobile agent framework named Maglog is proposed in this paper. In Maglog, a concept called “field” is introduced. By means of this concept, the following functions are realized: (1) agent migration, which is a function that enables agents to migrate between computers, (2) inter-agent communication, which is indirect communication with other agents through the field, (3) adaptation, which is a function that enables agents to execute programs stored in the field. We have implemented Maglog in a Java environment. The program of an agent, which is a set of Prolog clauses, is translated into Java source code by our Maglog translator, and is then compiled into Java classes by a Java compiler. The effectiveness of Maglog is confirmed through descriptions of two applications: a distributed e-learning system and a scheduling arrangement system.