The invention relates to the technical field of massagers and provides a head massager and a helmet size adjustment structure thereof. The helmet size adjustment structure comprises two racks and an adjusting device, wherein the adjusting device comprises a rotary shaft and a gear, the upper and lower parts of the gear are respectively meshed with all the racks, and a knob assembly and a lock assembly are arranged on the rotary shaft. The helmet size adjustment structure further comprises two tension springs, wherein the front end of each tension spring is fixedly arranged on a rear shell body, the rear ends of the tension springs are fixedly arranged on the two racks respectively, the knob assembly comprises a knob outer ring, a knob shell and a gear seat, the lock assembly comprises a knob lock catch, a knob lock catch upper cover and an elastic member, the gear seat is located in the knob lock catch, a unidirectional toothed ring is arranged on the gear seat, a lock catch which can be snapped into the unidirectional toothed ring is arranged on the knob lock catch, the elastic member is arranged on the knob lock catch upper cover, and teeth are further arranged on the gear seat and are meshed with the gear. According to the helmet size adjustment structure, knobs and buttons are designed into one body, and helmet adjustment is realized in two manners, so that the operating structure is more convenient, and the internal structure is more reliable.本發明屬於按摩器技術領域,提供一種頭部按摩器及其頭盔大小調節結構,頭盔大小調節結構包括兩齒條及調節裝置,調節裝置包括轉軸以及齒輪,齒輪的上部與下部分別與各齒條嚙合,轉軸上設有旋鈕元件以及鎖緊元件,還包括兩拉簧,各拉簧的前端固定於後殼體上,各拉簧的後端分別固定於兩齒條上,旋鈕元件包括旋鈕外圈、旋鈕外殼以及齒輪座,鎖緊元件包括旋鈕鎖扣、旋鈕鎖扣上蓋以及彈性件,齒輪座位於旋鈕鎖扣內,齒輪座上設有單向齒圈,旋鈕鎖扣上設有可卡於單向齒圈上的鎖扣,彈性件設於旋鈕鎖扣上蓋上,齒輪座上還設有齒牙,齒牙與齒輪嚙合,本發明中,旋鈕與按鈕設計為一體,通過兩種方式實現頭盔的調節,操作結構更方便,且內部結構更可靠。100‧‧‧前殼體200‧‧‧後殼體300‧‧‧齒條400‧‧‧調節裝置430‧‧‧齒輪蓋500‧‧‧旋鈕組件510‧‧‧旋鈕外圈520‧‧‧旋鈕外殼532‧‧‧齒牙700‧‧‧拉簧
