Filter element and filter device

A filter element comprising:

• a piezoelectric layer with a polarization axis direction;
• and
• a plurality of division resonators including at least four division resonators provided at the piezoelectric layer and defined by an acoustic wave resonator divided in series and in parallel;
• wherein
• each of the plurality of division resonators includes a functional electrode on the piezoelectric layer, each of the functional electrodes includes a high-potential electrode with a relatively high potential and a low-potential electrode with a relatively low potential;
• when a direction parallel or substantially parallel to a direction in which the high-potential electrode and the low-potential electrode face each other and oriented from the high-potential electrode toward the low-potential electrode is defined as an inter-electrode direction, and when a relationship in which a component of the polarization axis direction parallel or substantially parallel to the inter-electrode direction and the inter-electrode direction are in a same direction is defined as a forward direction relationship and a relationship in which the component of the polarization axis direction parallel or substantially parallel to the inter-electrode direction and the inter-electrode direction are in opposite directions is defined as an opposite direction relationship, a number of division resonators with the forward direction relationship is equal to a number of division resonators with the opposite direction relationship among the plurality of division resonators;
• and
• the plurality of division resonators include a first pair of resonators connected in parallel and a second pair of resonators connected in parallel, and the first pair of resonators and the second pair of resonators are connected in series.