Musk followed up with a tweet writing: "I've thought about and … I'm not sorry for party rockin."
Shiba, created in 2020 by the mysterious "Ryoshi", was originally a joke crypto based on the Doge meme.
Shiba first saw a major price spike in May this year, hitting A$0.00004938, before dropping again sharply.
Earlier this month, another tweet by Musk was credited for pumping the coin.
It comes as Bitcoin approaches its highest price ever. It was selling at A$84,091.93 on Monday. In April this year it hit A$84,879.65.
Bitcoin has had a rocky year, with prices plunging in May when Musk announced Tesla would no longer accept the cryptocurrency as payment.
The CEO of Tesla Motors cited environmental concerns about Bitcoin mining in his announcement.
Multiple crackdowns from Chinese authorities have also hurt the market.
However, cryptos across the board have surged this week after reports the US regulator will greenlight a Bitcoin futures exchange-traded fund.
Bloomberg reported the Securities and Exchange Commission is set to allow the first US Bitcoin futures ETF to begin trading next week, a step viewed as key by crypto investors to winning over more widespread adoption among the investing public.
Bullish crypto investors are predicting a "ludicrously strong" rally through the rest of 2021, Forbes reported.
"Bitcoin, ethereum and the broader crypto market are likely to have a ludicrously strong Q4, and I predict we will see new all-time highs across the board by 2022," Nick Spanos from Bitcoin Center NYC said.
Elon Musk's tweets are watched closely by traders. This week his fortune soared - he is now the world's richest person, with his net worth estimated at a massive US$230 billion (NZ$324.9b). That means he's worth more than Bill Gates and Warren Buffett combined.
He sent a sent cheeky message - a silver medal emoji - to his rival, Amazon founder Jeff Bezos, to mark the occasion.