The present invention relates to a cartridge of electric cigarette for preventing leakage. The cartridge may comprise a storing container 11 to store liquid therein; an extending tube 12 to have a guide tube 121 installed within the storing container 11 and extending in a hollow cylindrical shape, a lower fixing plate 122 coupled to the lower part of the guide tube 121 and secured to the lower part of the storing container 11 and a fixing gap 123 formed at the upper part of the guide tube 121; a guide lid 16 coupled to the upper part of the extending tube 12 and introducing evaporated component; an evaporating unit 17 fixed at the fixing gap 123; and a mouth piece 13 communicating with the guide lid 16 and coupled to the upper part of the storing container 11.