How do I migrate the content of a specific type? I wanted to backup all the contents of specific content type, and I want to install those data in different machine. Can anyone suggest me some good module which could help me do this?

I have tried the Backup module, and the Migrate module, but they back up the entire database. I want to backup specific contents alone but I couldn find any modules to do that.  

I could use either the Node Export module or the Feed module to back up specific content. Node export gives various options like you can export the data to CSV, XML or in text format which can be then imported using node import.
If you can get a CSV of the particular nodes you wish to migrate, then the Feeds module will do exactly what you want.

Worst comes to worst you can generate an RSS feed in Views of the content on your original site and then import using Feeds to the new site from that RSS feed.