An encoder that encodes a moving picture block by block, comprising: circuitry; and memory, wherein using the memory, the circuitry: selects a mode from among a plurality of modes each for deriving a motion vector, and derives a motion vector for a current block via the mode selected; and performs inter prediction encoding on the current block, using the motion vector derived, via one of a skip mode and a non-skip mode that is different from the skip mode, the skip mode being a mode in which a signal related to a motion vector difference and a signal related to a residual coefficient are not encoded, the non-skip mode being a mode in which a signal related to a residual coefficient is encoded, wherein the residual coefficient represents a prediction error of a sample of the current block, and the plurality of modes includes a plurality of first modes each for predicting the motion vector for the current block based on an encoded block neighboring the current block without encoding information indicating a motion vector into a stream, when a second mode included in the plurality of first modes is selected, the current block is encoded via the non-skip mode regardless of presence or absence of a residual coefficient, and when a third mode which is included in the plurality of first modes and different from the second mode is selected, the current block is encoded via the non-skip mode when a residual coefficient is present, and is encoded via the skip mode when a residual coefficient is not present, wherein the third mode is one of a frame rate up-conversion, FRUC, mode and a merge mode, characterized in that the second mode is a mode for predicting a motion vector corresponding to affine transformation, based on the encoded block neighboring the current block, in which it is expected that a residual coefficient having a nonzero value is generated among the plurality of first modes. circuitry; and memory, wherein using the memory, the circuitry: selects a mode from among a plurality of modes each for deriving a motion vector, and derives a motion vector for a current block via the mode selected; and performs inter prediction encoding on the current block, using the motion vector derived, via one of a skip mode and a non-skip mode that is different from the skip mode, the skip mode being a mode in which a signal related to a motion vector difference and a signal related to a residual coefficient are not encoded, the non-skip mode being a mode in which a signal related to a residual coefficient is encoded, wherein the residual coefficient represents a prediction error of a sample of the current block, and selects a mode from among a plurality of modes each for deriving a motion vector, and derives a motion vector for a current block via the mode selected; and performs inter prediction encoding on the current block, using the motion vector derived, via one of a skip mode and a non-skip mode that is different from the skip mode, the skip mode being a mode in which a signal related to a motion vector difference and a signal related to a residual coefficient are not encoded, the non-skip mode being a mode in which a signal related to a residual coefficient is encoded, wherein the residual coefficient represents a prediction error of a sample of the current block, and the plurality of modes includes a plurality of first modes each for predicting the motion vector for the current block based on an encoded block neighboring the current block without encoding information indicating a motion vector into a stream, when a second mode included in the plurality of first modes is selected, the current block is encoded via the non-skip mode regardless of presence or absence of a residual coefficient, and when a third mode which is included in the plurality of first modes and different from the second mode is selected, the current block is encoded via the non-skip mode when a residual coefficient is present, and is encoded via the skip mode when a residual coefficient is not present, wherein the third mode is one of a frame rate up-conversion, FRUC, mode and a merge mode, characterized in that the second mode is a mode for predicting a motion vector corresponding to affine transformation, based on the encoded block neighboring the current block, in which it is expected that a residual coefficient having a nonzero value is generated among the plurality of first modes.