Hey shinichi88,
Go into your ‘Project Settings’ and in the ‘Platforms’ section. Click on the ‘Android’ platform and find the option that says orientation. Click this dropdown to menu to expand your options for setting the orientation of your project. If you would like it to be compatible with landscape and portrait orientations, you can select the ‘Sensor’ option.
Android - Orientation
Let me know if this resolved your issue, or if you need further assistance.
Thanks,