In this paper the invariance of Quaternion Dirac equation under Lorentz Transformation, Charge conjugation, Parity
transformation and Time reversal operation has been discussed successfully. The invariance under the combined operation of
Charge conjugation, Parity and Time reversal (CPT) has also been discussed and expression for C, P, T and combined CPT
operators have been obtained in terms of quaternions. Invariance condition for electric and magnetic field has also been
obtained. It has been concluded that the Quaternion Dirac equation dominates over ordinary Dirac equation because of the
advantage of algebra of quaternions.
