A heater substrate for heating an alkali metal cell including an alkali metal includes a first heater wiring formed in a region surrounding an alkali metal encapsulating part in which the alkali metal is encapsulated; a second heater wiring formed in the region surrounding the alkali metal encapsulating part and inside the first heater wiring; and a third heater wiring formed outside the first heater wiring. A first electric current flowing in the first heater wiring is divided into a second electric current flowing in the second heater wiring and a third electric current flowing in the third heater wiring. A direction of the first electric current is opposite to a direction of the second electric current and a direction of the third electric current.