Hi @義弘 松島 👋 Thanks for your question!
At the moment, Miro doesn’t have a published limit for the number of layers you can create on a board. That said, performance can vary depending on the overall complexity of your board (number of objects, widgets, and collaborators).
If you’re working with multiple systems or large data diagrams, a good practice is to group related content into separate frames or even separate boards to keep things organized and performant.
If having a clear maximum number of layers is important for your workflow, I’d recommend sharing this idea in our Wish List so the product team can consider it for future improvements.