I know that the mic is a dual mono mini plug but I'm not sure if I get an extension cord it'll be compatible.
The manual of your camera says it uses a 3.5mm stereo mini plug and supplies 2 V. I don't know what the standards for DLSRs are, but I've found an image from Sennheiser which shows this:
This would mean it's using the tip as the power line as well as output, while the ring and the sleeve are grounded. Which means it's sending the signal unbalanced. I've checked the data for the ATR35 lav mic and it uses a similar layout, but with a mono plug.
I don't know what's the length that you require, but 5m would be about the absolute limit beyond which you will encounter more noise. For 2-3m you should be fine with just a headphone extension cable like this. For over 5m you'd preferably use a DI box to convert the signal to balanced and use a XLR connector to plug it into a recorder.
For more information on what a balanced signal is, see here. Hope that helps!