A convolutional neural-network calculating apparatus including a bidirectional-output operation module and a data scheduler is provided. The bidirectional-output operation module includes a number of bidirectional-output operators, a number of row-output accumulators, and a number of column-output accumulators. Each bidirectional-output operator has a row-output port and a column-output port. The row-output accumulators are coupled to the row-output ports, and the column-output accumulators are coupled to the corresponding column-output ports. The data scheduler is configured to provide a number of values of an input data and a number of convolution values of the convolution kernels to the bidirectional-output operators. In a first operation mode, the bidirectional-output operators output operation results to the corresponding column-output accumulators through the column-output ports. In a second operation mode, the bidirectional-output operators output operation results to the row-output accumulators through the row-output ports.