An ultrasonic sensing apparatus includes an accommodating shell and at least one detection device. The accommodating shell includes a base and a convex portion connected to the base. A side of the base has a first detection opening toward a first direction, and a side of the convex portion has a second detection opening toward a second direction. Each of the at least one detection device is disposed in the base or the convex portion of the accommodating shell and includes a board, a piezoelectric assembly, a housing and a plurality of fixing members. The plurality of fixing members are configured to fix the board on the top wall of the housing to press the board to the encapsulating body of the piezoelectric assembly, thereby pressing the piezoelectric sheet to the bottom wall.