Laterality designates a difference in the use of limbs and paired organs according to their position, right or left: one of the paired organs predominates over the other in the accomplishment of motor acts or in the perception of sensory signals. Brain lateralization has been widely studied, first in human species, then the existence of cerebral lateralization in non-human species, ranging from fish to primates, was highlighted. By determining the hand preferences in 64 common marmosets according to five behaviors (Grasp, Take to the mouth, Move, Handle, and Take out of mouth) performed during simple reaching, this study tries to highlight the marmosets' lateralization and the influence of the task complexity. Individuals were aged from 1.5 to 14 years and included 28 females and 36 males. Each individual was observed ten minutes once a day for one month while feeding. For each manipulative behavior, we recorded at least 20 occurrences. Despite strong individual preferences, no group bias was recorded. The strength of hand preferences appears to be influenced by the behavior: marmosets showed a lower laterality when handling the food. The impact of the posture has not been proved. No gender effects were revealed. Completed with the results of the project in which this study is performed, it seems that hand preferences are correlated with the complexity level of the task.