Funding has been given to developers who want to build the proposed racetrack on a site near Ebbw Vale.
The Wales Audit Office (WAO) said in April there were "significant shortcomings" in the way the government handed over the money.
But James Price defended the amount of public money put into the scheme.
The benefit for the economy meant it could be a "very high-impact output project", but it also carried "significant potential risk", the official in charge of the Welsh Government's economy department said.
He did not accept there were "shortcomings" in his department, but added: "I will accept that we have learned lessons."
He was giving evidence to the assembly's public accounts committee on Monday afternoon - the day before ministers will decide whether to give the circuit a £210m guarantee.
Deputy Permanent Secretary Mr Price said £55m had been spent on developing the plans, most of which had come from the private sector and £9.2m of which was grants and loans from the Welsh Government.
"Having gone through all of the files, spoken to all of the people concerned in some depth, I am persuaded that we have achieved value for money for what we have got, which is a project which is ready - subject to finance - to be delivered," he said.
The WAO also raised concerns about why the company was allowed to use a property development grant to buy a motorcycle engineering company in Buckinghamshire.
The company, called FTR, has since folded.
Mr Price could not confirm whether the minister in charge at the time, Edwina Hart, knew whether the grant was being used to buy the company, saying there was "no paperwork trail" to show she was aware.
On Tuesday the cabinet will discuss whether to underwrite around half the £425m cost of the Circuit of Wales.
It follows scrutiny of the business case as part of a due diligence process ordered by Economy Secretary Ken Skates.
There have been repeated delays to the scheme since it was first proposed in 2011, with previous proposals for government guarantees being rejected.
More than £9m spent by the Welsh Government on plans for the Circuit of Wales was good value for money, a senior civil servant has told AMs.