A hydraulic operating device is provided for a human-powered vehicle. The hydraulic operating device basically includes a base, an operating member and a handlebar mounting structure. The base includes a cylinder bore defining a cylinder axis. The operating member is pivotally coupled to the base about a pivot axis between a rest position and an operated position. The handlebar mounting structure is coupled to the base. The handlebar mounting structure defines a handlebar mounting axis that extends linearly along a handlebar in a mounted state. The cylinder axis is inclined towards the handlebar mounting axis as the cylinder bore extends away from the pivot axis as viewed in a pivot axis direction parallel to the pivot axis. The pivot axis is located in an area between the cylinder axis and the handlebar mounting axis as viewed in the pivot axis direction.