A recyclable formwork can suitably detect temperature of concrete cast contacting with the formwork in a field without spoiling the other functions of the formwork. The recyclable formwork is provided with: a main unit (1) including a plurality of ribs (3) and (4); a case (7) being housed between the ribs (3) and (4), the case (7) being fixed on a non-contact surface (1a); and a circuit housed in the case (7). A through-hole (16) is opened at a position corresponding to where the case (7) is fixed, the through-hole (16) penetrating the main unit (1) from the non-contact surface (1a) to a contact surface (2). A sensor-housing case (17) is provided with a lower portion of the case (7), the sensor-housing case (17) being inserted into the through-hole (16), a bottom face of the sensor-housing case (17) facing concrete. And, a concrete temperature-detecting sensor (19) for detecting surface temperature of the concrete is housed in the sensor-housing case (17).