Steven Lea, 40, of Chatsworth Drive, pleaded guilty to attempted robbery of the Premier Express store in Newmarket, Louth on May 31.
At Lincoln Crown Court today (Tuesday), Lea also admitted possession of an axe on the same occasion.
The charges follow an incident in which Lea went into the shop on the morning of the incident, and threatened staff with an axe.
He demanded cash but was challenged by staff and fled empty handed.
Judge Simon Hirst adjourned sentence until later this year, and Lea was remanded in custody.