A detection device includes a plurality of pyroelectric elements, detection circuit and a poling circuit. The pyroelectric elements include a first pyroelectric element through an n-th pyroelectric element serially provided between a detection node and a first power supply node with n being an integer equal to or greater than 2. The detection circuit is connected to the detection node. The poling circuit is configured to perform a poling process, in which a direction of polarization of at least one of the first pyroelectric element through the nth pyroelectric element is set independently of a direction of polarization of another one of the first pyroelectric element through the n-th pyroelectric element.