A signal transmitting member is electrically connected to a rotation sensing device and transmits a rotation sensing signal from the rotation sensing device to an external device. An internal structure holds the rotation sensing device and a portion of the signal transmitting member. At least one rib is molded on an outer peripheral surface of the internal structure. The internal structure is integrally molded with a resin material and includes an installing portion, which is configured to install the rotation sensing apparatus to an external subject body through the installing portion, and a holding portion, which is configured to enable holding of the rotation sensing apparatus through the holding portion. A plurality of recesses is formed between the installing portion and the holding portion.