Amazon founder Jeff Bezos flying to space on July 20

Amazon.com founder Jeff Bezos said Monday he is flying to space next month, just 15 days after he will step down from as CEO at the e-commerce company.

"Ever since I was five years old, I've dreamed of traveling to space," Bezos, 57, wrote as a post on Instagram. "On July 20th, I will take that journey with my brother. The greatest adventure, with my best friend."

Bezos will be going to space on the first crewed flight of the New Shepard rocket made by his aerospace firm Blue Origin, which he founded in 2000.

If achieved, he will beat SpaceX founder and CEO Elon Musk and Richard Branson's Virgin Galactic. The latter is expected to launch paying customers to space later this year or in 2022.

Bezos said last month he will step down from CEO role on July 5 -- exactly 27 years after the day Amazon was incorporated. Since founding the company from his garage as an online marketplace for books, the e-commerce firm quickly expanded to other sectors and surpassed Walmart as the US' most valuable retailer by market capitalization in 2015.

As of Monday, Bezos comes in second place with a net worth of around $186 billion, according to Forbes magazine's Real-Time Billionaires list.