To clarify the hatching dates and the growth of early life stage of the spotted mackerel, daily growth increments in otolith of 102 larvae caught from 36 stations in the northeastern waters off Taiwan were analyzed. The standard length of the larvae ranged from 2.8 to 9.1 mm and most of them were at flexion stage. The sizes of sagittae and lapilli from the newly hatched larvae were similar. Sagittae were much bigger than lapilli at the late growth stage. The simple regression analysis indicated that the growth of sagittae was more related to body depth and lapilli related to body length. The growth rates of the larvae of spotted mackerel increased with development stage, which were postflexion > flexion > preflexion, suggesting that the growth rate appeared in the late larval stage. Daily age of the larvae ranged from 2 to 14 days and the growth curve at larval stage was SL = 2.4 + 0.4 × Age. Hatching date backcalculated from the daily age of the larvae indicated that the fish spawned in the new moon.