Detection sensor

A detection sensor comprising:

• a sensor unit comprising:
• a vibratable film constituted by a piezoelectric film, configured to be irradiated with infrared rays and thereby generate first electric signals through a pyroelectric effect, and configured to be vibrated by sound waves and thereby generate second electric signals through a piezoelectric effect, and
• a case accommodating the vibratable film and including an opening disposed on one side in a first direction relative to the vibratable film, the first direction being a thickness direction of the vibratable film;
• and
• a holder comprising:
• a holding portion holding the sensor unit,
• a front portion disposed on the one side in the first direction relative to the case,
• a transmissive part configured to transmit at least infrared rays, the transmissive part being provided at the front portion, exposed from the front portion to the one side and the other side in the first direction, disposed on the one side in the first direction relative to the opening and the vibratable film, and opposed to the vibratable film,
• a sound hole to input therethrough sound waves, the sound hole being provided in a portion around the transmissive part of the front portion, the sound hole being open to the one side in the first direction, and
• a sound path extending from the sound hole to the opening of the case.