Provided is a stethoscope including: a support base having a first contact surface that comes into contact with an object to be measured, in which each of three first connection sides that are at least parts of sides defining the first contact surface is at least a part of each side of a triangle including the first contact surface; three elastic members having elasticity each of which has a second contact surface that has an obtuse angle formed with the first contact surface and that comes into contact with the object to be measured, the three elastic members being connected to each of the first connection sides in a second connection side having the same length as the first connection side out of sides defining the second contact surface; and three electrocardiographic electrodes that are disposed on each of the second contact surfaces and detect cardiac electrical activity of the object to be measured.