A method for converting heat into hydraulic energy comprises injecting a working fluid into a pneumohydraulic accumulator with contraction of the gas, subsequently expanding the gas with ejection of working fluid from another accumulator, and also supplying heat to the gas and removing heat from the gas, which operations can be carried out such that the average temperature of the gas is higher upon expansion than upon contraction. The gas is supplied with heat, causing the gas to be transferred via a hotter heat exchanger, and the heat is removed from the gas, causing the gas to be transferred via another, colder heat exchanger, wherein the gas is transferred between various accumulators via the above-mentioned heat exchangers. The apparatus for converting heat into hydraulic energy comprises at least two accumulators, means for supplying and receiving fluid, and also heating and cooling means, which comprise at least two continuous-flow gas heat exchangers which are mounted so as to be able to be used to transfer gas between gas reservoirs of various accumulators. The efficiency and rate of conversion of the heat into hydraulic energy are increased. Reliability and high power density are ensured.