QGISでOSMを開く

1. Go to Plugins → Manage and Install Plugins…
2. Search for and install: QuickOSM
3. Open it via Vector → QuickOSM → QuickOSM…
4. In the window:
   • Key: e.g., building
   • Value: leave blank or set e.g., yes
   • Extent: choose “Canvas extent” or a specific area
   • Click Run

You’ll get layers like:

• Points
• Lines
• Polygons (for buildings, land use, etc.)

geojsonとして書き出す