性冲动（英语：Libido）指人或某些动物见到、摸到、想到或听到与性相关的事物或声音，令人有一种兴奋的感官刺激，不能自制，尝试发生性行为。一些强迫性冲动有很多是与暴力、性相关的。

性冲动的来由可以心理学、生理学等多方面解说其原理。例如性冲动是一种条件反射。荣格认为性冲动不仅仅是性冲动，而且也是生命心灵中的一种类似气的力量，除表现在生长及生殖方面外，也表现于其他活动。

Libido (/lᵻˈbiːdoʊ/), colloquially known as sex drive, is a person's overall sexual drive or desire for sexual activity. Sex drive is influenced by biological, psychological and social factors. Biologically, the sex hormones and associated neurotransmitters that act upon the nucleus accumbens (primarily testosterone and dopamine, respectively) regulate libido in men and women. Social factors, such as work and family, and internal psychological factors, like personality and stress, can affect libido. Sex drive can also be affected by medical conditions, medications, lifestyle and relationship issues, and age (e.g., puberty). A person who has extremely frequent or a suddenly increased sex drive may be experiencing hypersexuality.