The present invention relates to a filter case for a shower having a function of adjusting a quantity of outflow of a filling material, the filter case including: a cylindrical body having a predetermined length and one end portion opened, for containing a filling material into the interior thereof; and an outflow quantity-adjusting means having a fixing part having one or more communicating holes adapted to communicate with the interior and exterior of the body, the fixing part being fitted to one end portion opened of the body and a rotating part having a discharge hole formed at the inside thereof in such a manner as to be passed through the upper and lower surfaces thereof, the rotating part being screw-coupled to the inner periphery of the fixing part so as to block the communicating holes of the fixing part.