Abstract: There are provided a method for producing a hydrogen gas-containing material in which higher safety than in a production method of the related art is secured and which is simple and has high production efficiency, and a method for producing a hydrogen gas-containing material and a device for producing a hydrogen gas-containing material in which it is possible to prevent nitrogen gas from being mixed into the hydrogen gas-containing material produced by the production method and it is easy to control an amount of hydrogen contained in the hydrogen gas-containing material. As one aspect, there is provided a method for producing a hydrogen gas-containing material including mixing a liquid composition containing a gelling agent or a thickener and a liquid medium with hydrogen gas in a line mixer (20) and cooling the liquid composition containing hydrogen gas in a liquid-transfer pipe (22) connected to the line mixer (20) and causing the liquid composition containing hydrogen gas to gel or thicken.