Resistance related to magnetic domain walls in compressive-strained epitaxial manganite ultrathin films has been studied. The samples were demagnetized in different ways to induce either multidomain or single domain states. Very large difference in resistance was observed between the two states, which was attributed to the domain wall resistance. The magnitude of the domain wall resistance was found to be different in different manganite compounds. We have shown that large domain wall resistance can be obtained in strained ultrathin manganite films and the result cannot be simply explained by the existing models.