Preference for artificial shelter with various height by the Japanese mitten crab Eriocheir japonica was studied. Three experiments were carried out. In experiment 1, E. japonica was a nocturnal species with a greater propensity to shelter during the daytime. In experiment 2 , among shelters of different height [crab body thickness (BT)×1,×2 ,×3,×4and×5], crabs significantly preferred shelters that height was between BT ×2 and BT×3. In experiment 3, natural specimens of E. japonica were hiding in the space (= natural shelter) with various height, that was formed under a boulder stone. Those height of space ranged from BT×1 to BT×11, and both the median and the mode was BT ×3. It was concluded that the most favorite space which was selected by E. japonica had a height from BT×2 to BT×3.