A hydrogen sensor 1 includes detection elements 4A, 4B, 4C formed from hydrogen-absorbing alloys which exhibit different hydrogen-absorbing pressures at a given temperature; a strain gauge 6 which detects changes in volume upon absorbing of hydrogen by the detection elements 4A, 4B, 4C; a micro-heater 2 which controls the temperatures of all the detection elements 4A, 4B, 4C to approximate equal values; and a substrate 3.