Shall I use anti virus program in my mobile phone?

I would like to suggest you that if you have a good smartphone with a good processor and RAM than you must use anti virus in it so that it can protect your device from viruses but if your device do no have the features mentioned above than you should not use anti virus as the anti virus will slow down such devices rather protecting them from viruses.

If you ask me for my personal opinion, antivirus is a waste for a smartphone.
It is enough with the security provided by the OS itself. Besides, nothing gets installed on your phone without your confirming it- unlike in PC. There are many points to support this logic:-
1. It has been estimated that less than 0.001% of apps installations evade Google's security measures. Even when there are thousands of malwares, there is no serious concern for Android users.
2. Google security has 7 layers of security measures:-
i) You get a unknown sources warning when you try to side load an app.
ii) You need to confirm installation. No app is installed without your confirmation. Will you confirm something that is suspicious?
iii) You need verify app permissions.
iv) Google conducts runtime security checks regularly to assess malicious behavior.
3. Some malware apps are just useless. When Google has a security in place, why pay for an app that practically does nothing is a waste of money and a waste on your resources like RAM, processor power, battery and storage space.
Those who root their phones and frequently download apps from 3rd party sources, yes- the threat exists. Even if you are rooted, and don't indulge in installing things from untrustworthy sources, you don't need an anti virus.
Finally, if you are really so scary of malware and virus, go for a free app. It will ease you of your worries, but will not be a burden on your pocket.

Antivirus protects the gadgets or devices from viruses. Some of the known antivirus are MacAfee, Norton and etc. However, if you're asking if we need to protect the mobile phones or smart phones with antivirus, my opinion is it depends on how do you normally use your mobile phones. Some points were already stated by our respectful editor Mr. Timmappa Kamat that Operating Systems of a certain mobile phone comes with antivirus itself. But, in some instances I would like to add that it also depends on how we normally use our mobile phones. If you are a person who normally use it for business purpose or business transaction, who would often login to your bank accounts, emails, and important personal information then you need to have a kind of anti- theft or anti-hacker software because the moment you login to your important information they could see what you are doing and they could copy it. That means, that antivirus alone can't deal with it because those phishing, spyware, malware and adware that they used to blend with the software can't be detected by the antivirus alone. This is the reason why in the United States they would protect their personal information with Life lock or other anti-malware, spyware and adware software because antivirus cannot detect them.