An atomizer (100) comprises a liquid storage member (10) and an atomization assembly (20). A liquid storage cavity (101) used to store an aerosol formation matrix is provided on the liquid storage member (10). The atomization assembly (20) is slidably connected to the liquid storage member (10), and comprises a heat generation structure (21) used to heat the aerosol formation matrix. The atomization assembly (20) is provided with a liquid inlet (202). A sealing member (30) is installed on the liquid inlet (202). An upper rod (40) is fixedly provided within and opposing the liquid storage member (10), and is connected to the sealing member (30). Sliding the atomization assembly (20) relative to the liquid storage member (10) enables the atomization assembly (20) to move between a first position and a second position. When the atomization assembly (20) is in the first position, the sealing member (30) closes the liquid inlet (202), and when the atomization assembly (20) is in the second position, the sealing member (30) is separated from the liquid inlet (202). The aerosol formation matrix passes through the liquid inlet (202) and comes into contact with the heat generation structure (21). In the atomizer (100), the aerosol formation matrix is separable from the heat generation structure (21), thereby preventing leakage and deterioration. Further disclosed is an aerosol generation device having the atomizer (100).