Ross McMullan's then home in Whitburn, in West Lothian, was searched and police found more than 30 kilos of the Class B drug in tubs inside shop bags.
McMullan, 32, was seen on 9 January outside the house in Townhead Gardens carrying the bags from a vehicle.
He was later spotted at another location in Whitburn and detained.
Officers then carried out a search at his home and found the drugs inside the shopping bags.
McMullan, now of Harthill, Lanarkshire, admitted being concerned in the supply of amphetamine when he appeared at the High Court in Edinburgh.
The court heard that although he had a criminal record he did not have previous convictions for drugs and had never served a jail sentence.
Defence solicitor advocate Ewen Roy said it was accepted that a prison sentence was likely to be inevitable and made no motion for bail to be continued.
Judge Craig Scott remanded McMullan in custody and continued the case for the preparation of a background report ahead of sentencing.
A drug trafficker has admitted having amphetamine worth more than £300,000 when police spotted him carrying heavy shopping bags in West Lothian.