Commenting on the visit the US state department said it was critical to "restore momentum to achieving our agreed common goal - the denuclearisation of the Korean peninsula".
"Hill is the most senior US official to visit North Korea since October 2002"Send us your views
Hill has said he expects six-nation talks on North Korea's nuclear programme will resume in early July.
The talks, hosted in Beijing, bring together the two Koreas, China, Russia, Japan and the US.
Funds row resolved
South Korea's Yonhap news agency said Hill's visit followed an invitation from North Korea and an apparent resolution to a row over frozen funds.
He is expected to meet Kim Kye-gwan, North Korea's vice-foreign minister and Hill's counterpart in the six-party negoatiations, for talks on denuclearisation and normalisation of North Korea-US relations, Yonhap said.
On February 13, 2007, at six-nation talks in Beijing, North Korea agreed to:
Start shut down of main Yongbyon nuclear reactor facility within 60 days of deal
Allow UN nuclear inspectors entry for all monitoring and verification
Discuss list of all nuclear programmes and materials including plutonium extracted from fuel rods
Declare all nuclear programmes and disarmament of all existing nuclear facilities
Begin talks on normalising diplomatic ties with the US and Japan, and resume high-level talks with South Korea
In return US, Russia, China, Japan and South Korea promise initial shipment of 50,000 tonnes heavy fuel oil within initial phase
The five nations agreed to establish working groups for initial and full implementation of action plan
Additional aid up to the equivalent of 1m tonnes of heavy fuel oil to be delivered to North Korea upon compliance
Hill plans to return to South Korea late on Friday to begin brief officials on his visit.
The visit comes a day after Hill said the North had finally taken hold of about $25m in frozen funds that had been held in a Macau-based bank.
The row over the funds had been the primary roadblock to implementing a six-nation deal agreed in February in Beijing under which North Korea pledged to shut down its main reactor.
With that dispute now apparently resolved, Hill had urged North Korea to "pick up the pace" on meeting its commitments under the Beijing agreement.
Hill is the most senior US official to visit North Korea since October 2002, when envoy James Kelly confronted Pyongyang with evidence that Washington said pointed to a covert uranium enrichment programme.
North Korea, which conducted its first nuclear test last October, said on Saturday it would re-admit inspectors from the International Atomic Energy Agency as required under the February deal.
Analysts say both Washington and Pyongyang are keen to see speedy results in the nuclear disarmament talks.
For its part North Korea is eager to receive energy aid promised under the February deal, as well as having trade sanctions imposed after its nuclear test lifted, and be removed from Washington's list of state
sponsors of terrorism.
While on the other hand Washington, faced with continuing bad news out of Iraq, is also eager to see concrete results from the disarmament talks before George Bush's presidency ends.