To easily measure the heart rate by providing a pair of electrodes exposed to the outside in contact with water on a float body floated on the water filled in a container such as a bathtub, and providing an arithmetic section amplifying, counting, and displaying the signal proportional to the heart beat detected by the electrodes.

A recess 2 is formed on a float body floated in a bathtub and made of aroma-emitting wood such as Japanese cypress for bathing while a pleasant sensation of aroma is enjoyed, and a case 5 storing an arithmetic section 3 and a digital display face 4 is buried in the recess 2. A pair of electrodes 6, 6 are fixed to the bottom face of the float body 1 in the exposed state, and they are connected to the arithmetic section 3 in the case 5. The arithmetic section 3 receives the pulse signal having the frequency proportional to the heart beat generated from the body of a measured person, the count value proportional to the heart beat is obtained when the number of pulses or pulse signal noises in a fixed time are clock-counted in one cycle period, and the count output is displayed on the digital display face 4.