Hydraulic excavator in digging at the construction machinery is a widely used mechanical device. Excavator attachments are taken with structural load and fatigue during digging under applied reaction. Fatigue analysis is done at joint pin between bucket and arm of front attachment at excavator under the force of hydraulic cylinder in operation. It is analyzed how load can be supported at the lower driving body applied on the bucket. In this study, the deformation of arm and the fatigue result are examined when reaction force is applied on the attachment of excavator.