A biological information acquisition device includes a body motion detector that includes a pressure sensitive portion on which a body motion of a subject acts and that detects a signal indicating the body motion of the subject, and a clamp member that clamps a clothing item of the subject. The clamp member includes a first member that is disposed on the subject side of the clothing item, and a second member that is disposed on the opposite side of the clothing item from the first member. The pressure sensitive portion is disposed on the first member side.
