Corruption is a clog in the wheel of progress in Nigeria and has incessantly frustrated the realization of noble national goals, despite the enormous natural and human resources in Nigeria. The article reviews the concept of corruption in line with its forms and effects on the Nigerian State, as well as corruption in public service from Prime Minister Tafawa Balewa's era to President Goodluck Jonathan's administration. The article examines the idealistic, resource curse, two public, low risk-high benefit and anomie theories, and consequently adopts resource curse, low risk-high benefit theories to explain causes of corruption in Nigeria. Also, some personal observations and data from Transparency International are utilized to explain corrupt practices in Nigeria. The article concludes that there is corruption in the Nigerian Public Sector because of societal pressure, tribalism, nepotism, low risk-high benefits of involving in corruption among others. The article recommends some measures to combat corruption in Nigeria.