An atomizer and an electronic cigarette comprising the atomizer. The atomizer comprises a liquid storage tube (1), a liquid adjustment assembly (2), and an atomization head (5). The liquid adjustment assembly (2) comprises an adjustment ring (21) and a first sleeve (22) sleeved on the periphery of the atomization head (5). The adjustment ring (21) is exposed outside the liquid storage tube (1). The atomization head (5) is provided with a first liquid-inlet (51), and the first sleeve (22) is provided with a second liquid-inlet (221). The adjustment ring (21) and the atomization head (5) are relatively fixedly connected, and through rotation of the adjustment ring (21), the first liquid-inlet (51) is communicated with or staggered from the second liquid-inlet (221). The atomizer enables a user to adjust, at the outside of the atomizer, an inflow amount of cigarette liquid into the atomization head (5).