For the traditional distributed computing system, the related message logging conditions had specified to keep the state consistence among the distributed process. Since many new characteristics are introduced in the mobile computing system, the new sufficient logging requirement for mobile computing has to be specified, to avoid the possible state inconsistence among the mobile nodes and the static nodes during the rollback recovery. Firstly, the related definitions of the inconsistence among the process state and the nondeterministic event were extended in the paper, independent of the specific log-based fault tolerant scheme. Finally, a novel particular logging consistency condition was derived based on the extended definitions and Piece-Wise Deterministic model for the mobile computing system. By contrast, the proposal is a practical and efficient constraint for mobile computing upon the possible failures.