A helmet massager and a helmet thereof are provided. The helmet massager comprises a helmet. The helmet comprises a first helmet body. The first helmet body comprises a first left helmet body and a first right helmet body which are butt jointed. The first left helmet body and the first right helmet body respectively have a first left rack and a first right rack. The helmet further comprises an adjusting device. The adjusting device comprises a base, a gear, a ratchet body with ratchet teeth, and a knob for driving the ratchet body to rotate. The base is located at a butt-joint site of the first left helmet body and the first right helmet body. Each of the first left rack and the first right rack engages with the gear. The ratchet body is positioned on the gear. The knob is mounted on the ratchet body. The base has a ring of locking teeth. The ratchet body has a rotating state and a rest state. When it is desired to adjust a size of a head room, the knob is turned in a forward direction or a reverse direction so that, via the ratchet body, the gear is driven by the knob to rotate. In this way, two adjacent butt-joint ends are driven by the gear to move away from or close to each other to change the size of the head room.