The main electric switch jumps randomly
There may be an overload, First off make sure all the other breakers are a lower value than the main. If one is higher than its likely overloading the Main. 

On each breaker there should be a value. In the US they are on the end of the switch. In that picture you posted they seem to be on the body prefixed with a "C". Those values are the number of amps a circuit will handle before the breaker trip. If the Main is higher then a branch then the branch will not trip because the main is tripping first. 

If thats not it then the main may be defective and would need to be replaced.