An elastic wave apparatus includes a piezoelectric substrate including a main surface and a polarization axis direction having a tilt angle with respect to the main surface, an IDT electrode provided on the main surface, and at least one line on the main surface and between an end edge of the main surface and the IDT electrode. A relationship a≤316|cos(θ)|μm is satisfied where a denotes a distance from the end edge of the main surface to the IDT electrode and b≥28 μm where a dimension of the line along a direction connecting the end edge to the IDT electrode is defined as a width, b denotes the width of the line when one line is provided, and b denotes the sum of the widths of multiple lines when the multiple lines are provided.