The Tesla and SpaceX boss was replying to a tweet from Game of Thrones actress Maisie Williams asking for investment advice. Bitcoin has seen its value surge to $17,400 (£13,000) in recent weeks after falling to as low as $5,000 (£3,777) earlier in the year.
This puts it less than $3,000 (£2,266) off the record value it achieved in 2017.
On Monday Ms Williams posted a poll on Twitter with the question “Should I go long on Bitcoin?”
More than 900,000 people took part in the poll with 53 percent voting no and 47 percent yes.
Among those who responded was Mr Musk, who earlier this week became the third richest person in the world.
Making a cryptic reference to a song from Netflix’s The Witcher series he said: “Toss a bitcoin to ur Witcher.”
Another Twitter user replied with a meme depicting a wizard and describing Bitcoin as “magic internet money”.
Mr Musk responded to this tweet with the emojis for a ghost and money, and a 2017 satirical article from The Onion which described Bitcoin as “ghost money”.
The comedic piece, published when Bitcoin was approaching its first peak, said: “At press time, bitcoin had recouped some of its losses, which experts attributed to the fact that even ghost money best suited for anonymously buying heroin could sometimes rebound.”
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It is a cryptocurrency which exists without any central bank and allows swift person-to-person transfers.
However, it has been criticised as a result of its volatility and use by criminals to fund their activities.
Joseph Stiglitz, a Nobel prize winning economist and former World Bank chief economist, has called for Bitcoin to be banned.
Speaking in 2017 he said: “Bitcoin is successful only because of its potential for circumvention, lack of oversight.
So it seems to me it ought to be outlawed. It doesn’t serve any socially useful function.
“It’s a bubble that’s going to give a lot of people a lot of exciting times as it rides up and then goes down.
“The value of a bitcoin today is expectations of what the bitcoin is going to be tomorrow.”
Earlier this week Mr Musk overtook Facebook founder Mark Zuckerberg to become the third richest person of the planet.
He is currently behind only Amazon chief Jeff Bezos and Bill Gates, co-founder of Microsoft.
Mr Musk’s wealth rose by $15bn (£11.3bn) when Tesla was added to the stock market index on Tuesday.