One of a series of pictures released after the rave showing people wanted in connection with offences
Joshua Colman, 21, entered the plea on Thursday at Lincoln Crown Court.
Dale Waring, 20, of Outwell, also admitted the offence.
In all 27 people have been accused of offences arising out of the rave at Twyford Woods, near Colsterworth, on Sunday, May 24 last year.
Police carried out an operation to close down the event which led to 21 officers and a police dog suffering injuries.
About 1,000 ravers attended the event and Lincolnshire police later described the level of violence shown towards thems as “totally unacceptable”.
The other defendants who admitted violent disorder are Benjamin Moore, 20, of Lowestoft; Joseph Collins ,27, of Lowestoft; Ross Porter, 29, of Blackwater, Camberley; Robert Cooper ,20, of Finchampstead, Berks; Thomas Carling ,18, of Corsham, Wilts; Anthony Davies, 30, of Tonypandy, South Wales; Richard Higgs,21, of Headingley, Leeds; Chris Willis,24, of Dunstable, Beds; Maggie-Mae Cross,20, of Carbrooke, Norfolk; Ashleigh Davies,34, of Tonypandy, South Wales; Adam Sheen,30, of Newport, Gwent; Scott Lamond,28, of Roath, Cardiff; Anthony Owens, 19, of Southmead, Bristol; Zachary King,20, of Lakenheath; James Long ,22, of Ampthill, Beds; and Dale Hopcroft ,22, of The Maltings, Norfolk.
Owens also admitted two charges of supplying drugs, a further charge of possession of cannabis with intent to supply and also illegal possession of ketamine.
Fabian Gibertoni, 19, of Sheffield, admitted possession of ketamine with intent to supply. Kirsty Wiggins,24, of Cirencester, also admitted possession of ketamine with intent to supply
They will be sentenced in July along with three other men who admitted violent disorder at an earlier hearing. They are Oliver Rickman-Williams, 23, of Stroud, Gloucs; Michael Carden,22, of Brimscombe, Gloucs; and Kieran Wilson,23, of Hoveton, Norfolk.
Three other defendants face trial after denying charges. Alan Brown ,31, of Bury St Edmunds, denied an offence of public nuisance by providing a generator for use at the rave. Jonathan Lawson,25, of Norwich, denied two charges of possession of drugs with intent to supply; Stephen Kelly ,26, of Bristol, denied possession of MDMA with intent to supply.
No pleas were taken from four other defendants. Glen More,23, of Stroud, Gloucs; Benjamin Richardson,18, of Metheringham, Lincs; Shea Bruce-Watson, 19, of Glastonbury. Somerset; are all accused of violent disorder. Samuel Stevens, 20, of Chipping Norton, is accused of possessing drugs with intent to supply.
A warrant was issued for the arrest of Alfie Clutterham ,18, of Ashley, Cambs, who failed to appear at court to answer a charge of violent disorder.