Surface acoustic wave resonator, surface acoustic wave oscillator, and surface acoustic wave module unit

A surface acoustic wave resonator comprising:

• a crystal substrate in which Euler angles are within a range of
• (−1°≦φ≦+1°,113°≦θ≦135°,40°≦|ψ|≦49°);
• an interdigital transducer having electrode fingers for exciting surface acoustic waves on the crystal substrate;
• a first region disposed at a center of the interdigital transducer;
• a second region and a third region arranged so as to sandwich the first region along a propagation direction of the surface acoustic waves, wherein
• a frequency being fixed in the first region and a portion in which a frequency gradually decreases as it approaches the edge of the interdigital transducer along the direction in which the surface acoustic waves propagate from a part adjacent to the first region is disposed in the second region and the third region, and
• when the frequency of the first region is Fa, the frequency at an edge of the second region on the opposite side of the first region along the direction in which the surface acoustic waves propagate is FbM, and the frequency at an edge of the third region on the opposite side of the first region along the direction in which the surface acoustic waves propagate is FcN, the variations in frequency at the edges are in the ranges of 0.9815<FbM/Fa<0.9953 and 0.9815<FcN/Fa<0.9953, respectively.