Click "Seismic hazard map" menu item which is a child of "Probabilistic Seismic Hazard Maps" on Download page and the following view appears.

You can select an archive format from "zip" and "tar.gz" using the radio buttons.
You can select a file format from "CSV file" and "Shape file" using the radio buttons.
You can select data range from "First-mesh" and "All over Japan" using radio buttons.
When clicking "First-mesh" radio button, the first-mesh map such as above figure appears.
You can select the first-mesh from clicking rectangular mesh in the map or clicking mesh code on the table.
You can select a reference date from the "Version" combobox.
You can select a earthquake category from the "Earthquake" combobox.
You can select a probability case from "Average Case" and "Maximum Case" using the radio buttons.
Click
to download the PSHM map data which are based on the settings mentioned above.