In the disaster site, mechanisms which can run on uneven and soft ground, and narrow space is needed. In this paper, we study omnidirectional crawler and propose 2 mechanisms, pitching-axis helical gear transmission and yawing-axis helical gear transmission, which transmit driving force by omnidirectional crawler with surface of contact. We design and prototype them by chain and rack gear. We also report about the first trial of them. In addition, we claim that the omnidirectional crawler mechanism can be used for not only mobile robot but also other applications. For example, when the omnidirectional crawler touch one object, the crawler is manipulator.