A encoding method for encoding a control parameter for controlling encoding of an image, the encoding method comprising: determining (S102, S103) a context for a current block in the image, from among a plurality of contexts; and performing arithmetic encoding on the control parameter for the current block, using the determined context to generate a bitstream corresponding to the current block; characterized in that the determining (S102, S103) further includes: determining a signal type under which the control parameter for the current block is classified; determining the context by using both of encoded control parameters for a left block and an upper block, when the signal type is a first type, the left block being a neighboring block to the left of the current block, and the upper block being a neighboring block on top of the current block; and determining the context by using a hierarchical depth of a data unit to which the control parameter for the current block belongs, without using any of the encoded control parameters for the left block and the upper block, when the signal type is a second type different from the first type; and wherein one of a split flag and a skip flag is classified under the first type, the split flag indicating whether or not the current block is partitioned into a plurality of blocks, and the skip flag indicating whether or not the current block is to be skipped; and wherein inter-prediction information is classified under the second type, the inter-prediction information indicating which of uni-prediction and bi-prediction is used for predicting the current block. determining (S102, S103) a context for a current block in the image, from among a plurality of contexts; and performing arithmetic encoding on the control parameter for the current block, using the determined context to generate a bitstream corresponding to the current block; characterized in that the determining (S102, S103) further includes: determining a signal type under which the control parameter for the current block is classified; determining the context by using both of encoded control parameters for a left block and an upper block, when the signal type is a first type, the left block being a neighboring block to the left of the current block, and the upper block being a neighboring block on top of the current block; and determining the context by using a hierarchical depth of a data unit to which the control parameter for the current block belongs, without using any of the encoded control parameters for the left block and the upper block, when the signal type is a second type different from the first type; and wherein one of a split flag and a skip flag is classified under the first type, the split flag indicating whether or not the current block is partitioned into a plurality of blocks, and the skip flag indicating whether or not the current block is to be skipped; and wherein inter-prediction information is classified under the second type, the inter-prediction information indicating which of uni-prediction and bi-prediction is used for predicting the current block. determining a signal type under which the control parameter for the current block is classified; determining the context by using both of encoded control parameters for a left block and an upper block, when the signal type is a first type, the left block being a neighboring block to the left of the current block, and the upper block being a neighboring block on top of the current block; and determining the context by using a hierarchical depth of a data unit to which the control parameter for the current block belongs, without using any of the encoded control parameters for the left block and the upper block, when the signal type is a second type different from the first type; and wherein one of a split flag and a skip flag is classified under the first type, the split flag indicating whether or not the current block is partitioned into a plurality of blocks, and the skip flag indicating whether or not the current block is to be skipped; and wherein inter-prediction information is classified under the second type, the inter-prediction information indicating which of uni-prediction and bi-prediction is used for predicting the current block.