A high purity (99.999%) copper single crystal was grown in Ar. atmosphere. Specimens were prepared by wire spark cutting and heat treated. Two annealing methods used were as follows: (1) isothermal annealing and (2) thermal cyclic annealing in which the temperature was changed between 1050$^\circ$C and 850$^\circ{C}$ with a period of 30 min.
To investigate dislocation distributions, they were obsevered with etching technique before and after heat treatment.
Etch pits at dislocations on the (111), (100), and (110) faces can be distinguished by shape.
