The main causes of depression in adults are adverse life events. In adverse life events, there is the death of a close relative, a crisis in marriage, chronic illness and unemployment. (Ching et al.,2017) First, the death of a close relative will experience in loss and grief which cause depression. A close relative is part of people’s lives. Since they live together for many years and get along for a long time. So they have a deep feeling. When there is the death of a close relative, people may disbelieve in reality death and difficult to trust it is truth. People feel guilt which they think it is their fault because they can’t save their close relative. Also, people will regret didn’t cherish the time together. With the continuous self-blamed can affect people sentiment then cause depression.Second, the crisis in marriage can cause depression. When the relationship occurs unresolved conflict, it will cause frequent quarrels. Then, result in anger and annoyance. With the continuous negative interactions, the relation will become worse. If the problem between a relationship can’t solve, it may divorce. In addition, there will be variously worried led by problems in the marriage. Such as finance, future or their child. These problems may disturb the mood of people.Then people suffer from depression. Third, chronic illness can cause depression. Such as cancer, stroke or diabetes. The illness can make people feel pain, appetite decrease or affect mobility. With the chronic illness, people life will have big changes. Patient mobility decrease can affect work and more serious patients cannot work. As a result, this not only affects the economic ability but also needs other people’s take care daily life. The patient may think they are the burden of the family. Also, they may feel guilty about their family and loss of hope of the recovery of illness.Fourth, long-term unemployment can be the cause of depression. Since work occupies most of the people lives. The loss of a job means loss of daily routines, people may have nothing to do and feel useless of themselves. Besides, the self-esteem of the unemployed will decrease, they cannot get satisfaction without work and feel the loss of status. In addition, loss of a job also the loss of social interaction. The communication channels of the unemployed will be fewer. Longtime lack communication with other will make the unemployed become lonely. So long-term unemployment can raise the various problem that cause depression.All of the above problems can cause depression in adults which it is a serious problem in Hong Kong but depression can be prevented by the appropriate method.