Aluminum alloy is one of the candidates for the liners of compressed hydrogen tank mounted to fuel cell vehicles. It is crucial to elucidate the behavior of hydrogen in the alloy sheet with one side being exposed to hydrogen gas. In the present work, using the hydrogen microprint technique, in 6061 and 7075 aluminum alloy sheets, relationship between hydrogen pressure and the molar quantity of hydrogen emitted from the inside has been investigated. Under any pressure, the quantity of emitted hydrogen is about 10 times smaller in the 7075 alloy than in the 6061 alloy. This indicates that the amount of hydrogen atoms accumulating in the 7075 alloy may be much larger than that in the 6061 alloy.