Provided is an internal switch-type salt meter in which an impact switching device operable by an impact applied into a main body is built in the main body so that it is unnecessary to separately waterproof the switching device. The salt meter includes a main body having the inside waterproofed against the outside, a sensor part disposed on an end of a side of the main body to detect salinity of an object to be measured, a display part disposed on a surface of a side of the main body to display a result measured by the sensor part, and a switching device built in the main body to generate a contact point by an impact with an external impact object, thereby operating the sensor part and the display part. The switching device may be built in the main body so that a separate waterproof process is not required.