Canadian superstar Justin Bieber has posted his first video to Instagram, which shows him shirtless and in fits of giggles throughout.

The 19-year-old singer recorded the short 15-second clip and posted it on the popular social media platform on Thursday (June 20).

Wearing a black baseball cap on backwards and a silver chain around his neck, Bieber burst into laughter while addressing his fans in the video.

He said to camera: "So, crazy news guys! There is video on Instagram."

Bieber took to Twitter to share the video, writing next to an accompanying link of the clip: "And if u already didn't know... Hahaha....more coming soon :) (sic)."

Bieber's disposition has sparked concern among some fans though, with speculation rife that the star had been smoking marijuana before filming the clip.

One fan wrote: "Justin bieber was stoned in that IG video," while another claimed: " Justin Bieber was completely stoned in his video on Instagram (sic)." Watch the video here: