An open‐type steel Sabo dam is mainly constructed as a protective structure on debris flow. In load bearing capacity evaluation, despite the difference of trapping mechanism, design manual of an open‐type steel Sabo dam is utilizing the design concept of a closed‐type Sabo dam. However, the effect of structural permeability on the debris flow load is unclear from viewpoint of dynamic debris flow load. This study experimentally evaluates the effect of structural permeability of open‐type steel Sabo dam as a dynamic debris flow load. The experiment focuses on overturn limit state by using an experimental device can rotate when debris flow exceeds at the failure limit. Difference of a dynamic debris flow load distribution between an open‐type and a closed‐Sabo dam model under same conditions was revealed. Also, moment load on closed‐type Sabo dam is larger than that on the open‐type one.