Abstract: A light therapy device includes a base, a circuit board, a power supply unit and a lid. The base includes a bottom surface, wherein a first accommodating space is formed in the base. The circuit board is disposed in the first accommodating space. The circuit board includes a lighting unit and an electrode set electrically connected to the lighting unit, in which the lighting unit emits light toward the bottom surface. The power supply unit is electrically connected to the electrode set. The lid has a second accommodating space for accommodating the power supply unit, in which the second accommodating space is eccentrically rotated relative to the first accommodating space for eccentrically rotating and switching the power supply unit to be conducted or non-conducted with the electrode set, thereby turning on or off the lighting unit.