This article describes theoretical considerations of the emotional stability, which is one of the important professional quality of the teachers from the primary school. The emotional stability has two basic functions: - The emotional adjustment function of the emotional stability has the role of adjustment and stability, allows to keep up the emotional equilibrium, stumbles the uncontrollable growing of the emotional tension until the level of bewilderment, of disorganization of the activity and of the emotional frustrating experiences. - The adaptable function of the emotional stability permits flexible adaptability, adequately for the changes, without negative results from the emotional reaction. It is contribute to keep up the dynamic equilibrium between intern emotional mood and extern emotional mood. It is also contribute to achieve a maximum efficiency in emotional reactions and behavioural in stressful situations. The functions of the emotional stability are in a permanently interactions and are connected between them at the reflection of emotional sphere of a personality.