An illuminating device mainly includes a tube-like lamp disposed in a main body. The tube-like lamp has two terminal portions adapted for electrically connecting to a power source and a bending portion between the terminal portions. The main body is provided with a support having two hooked portions configured to support the tube-like lamp. The present invention further provides another tube-like lamp characterized by having a buffer part securely attached on the bending portion for lessening or absorbing the shock of an impact on the tube-like lamp. The support may has a gap between the hooked portions such that the tube-like lamp fit with sufficient tightness into the gap between the hooked portions thereby immobilizing the tube-like lamp more efficiently and absorbing the shock.