I would like to know, if someone takes a new job within 3 months prior to applying for UK visit visa, is there any specific rule for that? I have browsed in Google but couldn't find appropriate answer. Please help me regarding this matter.
As @DumbCoder mentioned, changing jobs is no big deal as people do it all the time. As long as you provide documents backing it up and all the necessary paperwork required for the visa you should be fine, just prepare well and make sure you have everything.