The notion of aspect is important as a systematic approach to the representation of cross-cutting concerns and the incremental additions of new functionalities to an existing system. Since UML is a modeling language used in early stages of software development, studying how UML is related to aspectual software is an important topic. This paper proposes a way of introducing the join point model (JPM) to UML/STD. The proposed extension is smoothly integrated with the core part of the execution semantics adapted by the UML standard. Categories and Subject Descriptors D.2.1 [Software Engineering]: Requirements/Specifications; D.2.2 [Software Engineering]: Design Tools and Techniques; D.2.4 [Software Engineering]: Software/Program Verification General Terms Design Keywords UML State Diagrams, Join Point Model, SPIN