Preference for artificial burrows by the endangered Japanese crayfish species Cambaroides japonicus was studied to improve its cultivation. The occupation of artificial burrows, which were made from straight polyvinyl chloride pipes of different internal diameters (Y, mm), by crayfishes of different total lengths (X, mm) was significantly (P <0.001, n=56) described by a linear regression: Y= 0.49X + 3.42 (19.0 less than or equal to X less than or equal to 70.2). Among burrows of different lengths [crayfish total length (TL) x 1, x 2, x 3, and x 4], crayfishes significantly preferred burrows that were greater than TL x 3 (P <0.001, n=588).