A liquid pressure motor comprising: a first inlet/outlet port and a second inlet/outlet port both connected to a direction switching valve; a first inlet/outlet passage which connects the first inlet/outlet port with a liquid pressure motor mechanism; a second inlet/outlet passage which connects the second inlet/outlet port with the liquid pressure motor mechanism; a counter balance valve; a bypass passage which connects the first inlet/outlet passage between the counter balance valve and the liquid pressure motor mechanism with the second inlet/outlet passage between the counter balance valve and the liquid pressure motor mechanism; a connection valve which is provided in the bypass passage and is opened when a fluid pressure in the first inlet/outlet passage or the second inlet/outlet passage becomes not lower than a working pressure; and a pilot passage which introduces a fluid pressure to a back pressure chamber of a connection valve by which chamber a working pressure of the connection valve is controlled, characterized in that the counter balance valve is connected to the first inlet/outlet passage and the second inlet/outlet passage, in that the pilot passage is connected to the counter balance valve, in that a switching valve connected to the pilot passage is provided to have a first changeover position where the back pressure chamber is connected to the tank and a second changeover position where the pilot passage is connected to the back pressure chamber, and in that the liquid pressure supplied to the liquid pressure motor mechanism is introduced by the switching valve into the back pressure chamber via the pilot passage when the liquid pressure motor mechanism is in operation, whereas, when the liquid pressure motor mechanism is being braked, the back pressure chamber is connected to the tank when the fluid pressure in the pilot passage becomes equal to or lower than a predetermined pressure. a first inlet/outlet port and a second inlet/outlet port both connected to a direction switching valve; a first inlet/outlet passage which connects the first inlet/outlet port with a liquid pressure motor mechanism; a second inlet/outlet passage which connects the second inlet/outlet port with the liquid pressure motor mechanism; a counter balance valve; a bypass passage which connects the first inlet/outlet passage between the counter balance valve and the liquid pressure motor mechanism with the second inlet/outlet passage between the counter balance valve and the liquid pressure motor mechanism; a connection valve which is provided in the bypass passage and is opened when a fluid pressure in the first inlet/outlet passage or the second inlet/outlet passage becomes not lower than a working pressure; and a pilot passage which introduces a fluid pressure to a back pressure chamber of a connection valve by which chamber a working pressure of the connection valve is controlled, characterized in that the counter balance valve is connected to the first inlet/outlet passage and the second inlet/outlet passage, in that the pilot passage is connected to the counter balance valve, in that a switching valve connected to the pilot passage is provided to have a first changeover position where the back pressure chamber is connected to the tank and a second changeover position where the pilot passage is connected to the back pressure chamber, and in that the liquid pressure supplied to the liquid pressure motor mechanism is introduced by the switching valve into the back pressure chamber via the pilot passage when the liquid pressure motor mechanism is in operation, whereas, when the liquid pressure motor mechanism is being braked, the back pressure chamber is connected to the tank when the fluid pressure in the pilot passage becomes equal to or lower than a predetermined pressure.