A shock absorber, including a first casing, a second casing, a frame, a vibrator, and a buffer element, is provided. The first casing includes a first pressing portion. The second casing is detachably fixed to the first casing and includes a second pressing portion. The frame includes a first portion and a second portion, and the first portion is located between the first pressing portion and the second pressing portion. The vibrator is fixed to the second portion of the frame. The buffer element is disposed between the first pressing portion and the first portion of the frame, and between the second pressing portion and the first portion of the frame. The first pressing portion and the second pressing portion press against the buffer element to sandwich the first portion of the frame. A projection device with the shock absorber is also provided.