HYDROGEN LEAKAGE DETECTION SYSTEM

A hydrogen leakage detection system for detecting a hydrogen leakage in a fuel cell system includes: an outer shell configured to accommodate a hydrogen flow section; a hydrogen sensor; and a porous sheet disposed to delimit at least a part of a space within the outer shell and allowing permeation of hydrogen through the porous sheet in a thickness direction thereof. The hydrogen flow section is disposed in a region below the porous sheet, and the hydrogen sensor is disposed in a region above the porous sheet.