The experimental setup, test method and laser performances at room temperature for a neodymium pentaphosphate laser with a single transverse mode longitudinally pumped by a dye laser at 0.58μm are described. The optical slope efficiency is -10%, threshold energy for single transverse mode is -40μj. Oscillation threshold for single mode of longitudinal pumping was estimated with a simple computer model. They agree each other within the experimental error of 10%. A single pulse without Q-switching can be obtained by appropriately varying the cavity parameters.