  The single qubit quantum teleportation (sender and receiver are Alice and Bob
respectively) is analyzed from the aspect of the quantum information theories.
The various quantum entropies are computed at each stage, which ensures the
emergence of the entangled states in the intermediate step. The mutual
information $S(B:C)$ becomes non-zero before performing quantum measurement,
which seems to be consistent to the original purpose of the quantum
teleportation. It is shown that if the teleported state $|\psi>$ is near the
computational basis, the quantum measurement in $C$-system is dominantly
responsible for the joint entropy $S(A,C)$ at the final stage. If, however,
$|\psi>$ is far from the computational basis, this dominant responsibility is
moved into the quantum measurement of system $A$. A possible extension of our
results are briefly discussed.
