  We study the magnetic properties of $S=1/2$ antiferromagnetic Heisenberg
chains with inhomogeneity of interaction. Using a quantum Monte Carlo method
and an exact diagonalization method, we study bond-impurity effect in the
uniform $S=1/2$ chain and also in the bond-alternating chain. Here `bond
impurity' means a bond with strength different from those in the bulk or a
defect in the alternating order. Local magnetic structures induced by bond
impurities are investigated both in the ground state and at finite
temperatures, calculating the local magnetization, the local susceptibility and
the local field susceptibility. We also investigate the force acting between
bond impurities and find the force generally attractive.
