Did you add capacitors to the input & output?
From the datasheet:
Please attach a capacitor (greater than 0.33μF) between the Vcc and GND.
The capacitance values will differ depending on the application, so please take this into account when configuring the terminal......Please attach an anti-oscillation capacitor between Vo and GND. The capacitance of the capacitor may significantly change
due to factors such as temperature changes, making it impossible to completely stop oscillations. Please use a tantalum
capacitor or aluminum electrolysis capacitor with favorable characteristics and small internal series resistance (ESR) even
at low temperatures.