There seems to be no limit as such.
However if you carry more than 10'000 €, you might have to declare it depending on the country.
For example in Germany , you are to declare it when orally asked to do so.
For the UK on the other hand, there seems to be no need to do so.
So if you consider taking more than 10'000 €, you should check the rules for the specific country you are flying to.
travel.stackexchange.com/users/8363/drat
Assuming a maximum luggage allowance of 20kg, and that the weight of 1m EUR is about 2kg .
Then we are talking about 10 million Euros.
:D
Of course that is assuming that you are too poor to pay for extra allowance.
travel.stackexchange.com/users/13015/Aron
Apart of regulations mentioned by drat , EU also has anti-money laundering laws.
They apply regardless if you travel internationally or not.
The EU directive 2005/60/EC "on the prevention of the use of the financial system for the purpose of money laundering and terrorist financing" tries to prevent such crime by requiring banks, real estate agents and many more companies to investigate and report usage of cash in excess of €15,000
How this directive is implemented in practice depends on each member state.
travel.stackexchange.com/users/727/vartec
On a recent trip to Greece (3rd August 2015)
I was stopped at Gatwick airport South for the random bag search and was asked about the cash I had in my wallet.
It was 1500 euros plus £300 UK.
I was told that part of the Euros could be confiscated as it was 'over limit'.
after a behind the scenes discussion between customs officials I was allowed to 'keep it'.
That was purely personal experience
and I don't know where this approach came from.
I too thought there was no limit in the EU.
travel.stackexchange.com/users/33015/Matthew
What nonsense.
In the UK there is no limit to amount of cash you can take out to another European state.
The treasury department currently have abandoned restrictions although this can be changed at any time.
However beware POCA (proceeds of crime act) and money laundering act.
This means that any large amount can be seized by police, customs or UK border.
They have a time limit to put you in front of a magistrate who will decide if you can keep it or not.
My advice be respectful and honest.
Prove where money came from (eg bank receipt, statement), prove what money is for (eg expensive hotel car, holiday home charges etc) with paperwork and they should let you go.
More than say 10 or 12 grand may be a problem but no one will state how much.
The officer can decide.
Good luck!
travel.stackexchange.com/users/41583/Alan
With in the EU there is a freedom of capital moment.
However, having said the above you need to know that up to €10.000 cash no questions are asked.
For larger amounts like €50.000 or €100.000+ you would be asked to prove the source of that cash.
(money laundering regulations).
Also you would be asked the reason for moving this kind of money in cash.
As long as you have a legitimate source for that money and a legitimate reason to take that money in another country, I don't see a problem.
Kindly note that for Tax purposes you will have to declare the movement of cash to the customs if you don't declare the cash at the customs and you get caught (most probably you will), you will be in serious troubles.
You might even spend a night or two in jail.
Better safe than sorry.
travel.stackexchange.com/users/20150/Apterea
There is only a reporting limit of 10.000 EUR when entering from outside.
The rules which are actually often misquoted, does not require you to report any cash travelling within the EU
travel.stackexchange.com/users/20149/Michael
Is there any specific limit of money you can carry on cash while flying from one European Union country to another?
How much cash can you carry on a flight within the European Union?
travel.stackexchange.com
<air-travel><europe><money><international-travel>
travel.stackexchange.com/questions/26117
travel.stackexchange.com/users/6997/fedorqui
There is no limit to the amount of cash you can take within the EU, and you are not required to report it. However, there is a reporting limit of 10,000 EUR when entering from outside, and you may be asked to prove the source of larger sums of cash. There are no limits to moving cash within the EU although there is some missunderstanding about the 10000 EUR reporting rule. This rule in fact only applies to travellers from outside the EU. Travellers within the EU may, however, be asked to prove the source of very large amounts of cash.
There are no limits for transporting cash within the EU. There is some misunderstanding about the 10000 EUR reporting limit. It does not apply inside the EU, only to people entering from outside  Passengers may be asked to prove the source of larger sums.