A glass panel unit manufacturing method comprising: a providing step of providing a first substrate including a glass pane and a second substrate including another glass pane; a pillar arrangement step of arranging a plurality of pillars on one surface of the second substrate; a gas adsorbent placement step of placing a gas adsorbent on the second substrate; a bonding step of bonding the first substrate and the second substrate together with a sealing material in a frame shape by heating in the furnace to a predetemined temperature higher than the melting point of the sealing material so as to create an internal space in which the plurality of pillars and the gas adsorbent are located between the first and second substrates (10, 20) and the sealing material; an evacuating step of evacuating the internal space; a sealing step of sealing the internal space while keeping the internal space evacuated; and an activating step of heating the gas adsorbent placed in the internal space to a predetermined activation temperature the gas adsorbent including: a first gas adsorbent containing a non-metallic getter material having a porous structure with the ability to adsorb gas molecules; and a second gas adsorbent containing a metallic getter material having a metallic surface with the ability to adsorb gas molecules, and the activating step including activating the first gas adsorbent while performing the evacuating step inside the furnace, and activating the second gas adsorbent by locally heating the second gas adsorbent outside the furnace a providing step of providing a first substrate including a glass pane and a second substrate including another glass pane; a pillar arrangement step of arranging a plurality of pillars on one surface of the second substrate; a gas adsorbent placement step of placing a gas adsorbent on the second substrate; a bonding step of bonding the first substrate and the second substrate together with a sealing material in a frame shape by heating in the furnace to a predetemined temperature higher than the melting point of the sealing material so as to create an internal space in which the plurality of pillars and the gas adsorbent are located between the first and second substrates (10, 20) and the sealing material; an evacuating step of evacuating the internal space; a sealing step of sealing the internal space while keeping the internal space evacuated; and an activating step of heating the gas adsorbent placed in the internal space to a predetermined activation temperature the gas adsorbent including: a first gas adsorbent containing a non-metallic getter material having a porous structure with the ability to adsorb gas molecules; and a second gas adsorbent containing a metallic getter material having a metallic surface with the ability to adsorb gas molecules, and a first gas adsorbent containing a non-metallic getter material having a porous structure with the ability to adsorb gas molecules; and a second gas adsorbent containing a metallic getter material having a metallic surface with the ability to adsorb gas molecules, and the activating step including activating the first gas adsorbent while performing the evacuating step inside the furnace, and activating the second gas adsorbent by locally heating the second gas adsorbent outside the furnace